Installing OpenCPN

• Download the installation package for Windows from Download OpenCPN.
• Use the stable release for navigation en route, or if you just started using OpenCPN.
• Exit all other programs, including your anti virus program - known to create problems in some cases. Unplug your network cable, to be on the safe side.
• Run the downloaded installer. Re-start your anti-virus. Re-connect the network
• If upgrading from a previous version of OpenCPN, there is no need to un-install the old version. Simply install the new version and it will upgrade OpenCPN, saving all your existing configuration and preferences.
• If this is a new installation, click on the Toolbox icon and configure your GPS source, chart directories, and other settings.
• If your installation goes well, but OpenCPN don't start as expected, try to download and install these runtime components.
• Not Supported Windows versions:
  Win 8 RT is not supported.
  Win CE is not supported.
  Win XP SP 2 or 1 are not supported. The last OpenCPN version that included support was 2.6.1624.
  Win 2000 is not supported. The last OpenCPN version that included support was 2.5.0.
  Win 98/ME are not supported. The last OpenCPN version that included support was 2.1.0.
• Old versions of OpenCPN are available on SourceForge.

Linux

32/64 bit Ubuntu/Debian Distributions

32/64 bit Fedora / Cent OS

• For Debian based Linuxes: Make sure that you belong to the "dialout" group. To find out, run the "$groups" command. If you're not in "dialout", add yourself with the command "$sudo usermod -a -G dialout $USER". Check this straight away, it will save you from frustration later on. If there is a problem connecting the GPS to a physical port, such as /dev/ttyS0, the reason is probably that you don't belong to "dialout".
• For other Linux distributions, replace "dialout" above, with the result of this command: $stat -c %G /dev/ttyS0
• It is recommended that you install the "xcalib" program, that is necessary to dim the screen for night time usage. Use your favourite package manager or just issue $sudo apt-get install xcalib from the command line (for debian based distros).
• It is recommended that you install the "xdg-utils" program, that helps the grib plugin compose a SailDoc grib-request-mail. Use your favourite package manager or just issue $sudo apt-get install xdg-utils from the command line (for debian based distros).
• On Ubuntu, start "System->Administration->Synaptic". In Synaptic go to "Settings->Repositories" and tick the box "Community-maintained Open Source software (universe)". Close Synaptic.
• Download the correct .deb or .rpm from Download OpenCPN.
• For Ubuntu, only use the download with an Ubuntu version number if you have exactly that version. Otherwise use the link "Download OpenCPN 3.X.X for all other *Ubuntu's".
• Use the stable release for navigation en route, or if you just started using OpenCPN.
• Click on the downloaded package. An installation manager will guide you on most Linux distributions. All dependencies should automatically be installed. For most Linux installations, this is all you have to do. Consult the following 3 paragraphs if you run into trouble.
• If you have problems with dependencies, run the recommended command line in the next paragraph. First check that you really have downloaded the correct version of OpenCPN. se above.
• sudo gdebi <downloaded_opencpn_file.deb>. The command "gdebi" will automatically install the dependencies for you.
• It is also possible to install the package via dpkg or rpm, on the condition that all dependencies are met.To make sure that this is the case on Ubuntu, open a terminal window to get a command line, (Applications->Accessories->Terminal) and copy and paste the following line: "sudo apt-get install libwxgtk2.8-0 libwxbase2.8-0 wx-common libglu1-mesa libgl1-mesa-glx zlib1g bzip2 gpsd gpsd-clients xcalib xdg-utils libportaudio2 libkml0 libtinyxml2.6.2 liburiparser1 zlib1g libexpat1". Then proceed with the commands below

  • For Ubuntu: $ sudo dpkg -i <downloaded_file.deb> 
    For Fedora: # sudo yum install --nogpgcheck <downloaded_file.rpm>

  • The binary will be installed to /usr/bin/opencpn and the static data used by the program will be in /usr/share/opencpn
• If this is a new installation, click on the Options icon and configure your GPS source, chart directories, and other settings.
• If there is a problem with sound, make sure that you, as a user, belongs to the "audio" group. To find out, run the "$groups" command. If you're not in "audio", add yourself with "$sudo usermod -a -G audio $USER"
• If you are running Debian Squeeze and want to install OpenCPN from the distributions .deb package, you will need to install with something like this in order to satisfy install dependencies related to libtinyxml:
  $sudo dpkg -i --force-depends opencpn_3.1.1327-1_i386.deb

Using Linux repositories, an easier way to install and update.

Installing in a different, easy way.

Installing on Ubuntu

Have a look at opencpn on launchpad.net.
The launchpad site can be used as a repository, and let OpenCPN be downloaded and updated the mainstream Ubuntu way. The X86 architecture has always been supported. From early autumn 2014 experimental packages for ARM will be available as well.
Add repositories in, for example, Synaptic, like this:
10.04
=====
- Add the following Software Sources: PPA from
https://launchpad.net/~opencpn/+archive/opencpn, universe, lucid-backports
- In Synaptic, reload the software sources as it suggests, search for
and install opencpn
- No need to install anything manually
11.04
=====
- Add the following Software Sources: PPA from
https://launchpad.net/~opencpn/+archive/opencpn, multiverse, universe,
natty-backports
- In Synaptic, reload the software sources as it suggests, search for
and install opencpn
- No need to install anything manually

Installing on Fedora

A full repo is now available and can be used to install and update opencpn.
To install the repo, please run this as root:
yum install http://je.onfray.fr/repo/fedora/18/x86_64/jeo-release-1.0-1.fc18.noarch.rpm
You can install the above rpm, no matter if you're using i386 or x86_64, be it Fedora 16, Fedora 17 or Fedora 18, it'll work on all these (you should be able to install it right from your browser clicking the above link and then install)
By default, only the stable repo is enabled ; you can install opencpn-4.0 from your favorite package manager (yum, Gnome package kit or KDE package kit). I've created two separate packages: "opencpn" with the program and the two default plugins and "opencpn-doc" with the whole html doc to browse it offline.
When a new stable is released, you'll be automatically notified and able to update... so easy!

Security/Trust: all packages are signed with Key ID 7e53dbe19add462d

Other 32, 64bits, the armhf architecture, Linux Distributions and the BSD operating systems

• Currently other distributions requires compiling the source. This will involve resolving various dependencies and is for folks comfortable with developing on Linux.
• Download the source from sourceforge.net or directly from the Git server. The SourceForge link for this project is sourceforge.net/projects/opencpn/. More about compiling on Linux here Compiling - Linux.
• Interested in maintaining a package for your favorite Linux distribution? Follow the SourceForge link above.
• This also includes the different BSD distributions. Report your experiences back to the forum.

Mac OS X

• Installation OpenCPN on Mac OS X is no different from installing other programs. If a previous version is installed, rename the old version (app) file to avoid overwriting.
• The Mac package is a ".dmg" file, and to install OpenCPN, the dmg file has to be opened (it will mount as a virtual device) and the app icon in the opened device window must be dragged and dropped to the application folder.
  After that the device window can be closed and the mounted virtual device can be ejected.
• You can have a look at this tutorial for general instructions on installing an application on Mac OS X.
• If you have a message, that installations are only accepted for programs from qualified developers, go to System Settings / Security, first Tab, and switch to "No Constraints".
  After installation switch back, to prevent installation of malware.

Different versions of OpenCPN

• Use a "stable", official release for actual navigation. The latest stable release is always available at the top of the download page or from Source Forge.
• Beta releases are snapshots of the development process, and may contain errors or temporarily be unstable. Show stoppers are normally fixed very quickly however. This is where the latest features first are seen. Most of the time the beta releases are quite stable and the OpenCPN team appreciate it if more experienced users test the releases and report back.
• The place to report bugs and suggest features is the Tracker. To reach the Tracker from the OpenCPN Web pages click on the "Tracker" tab at the upper right (above the blue bar). The sticky thread "Tracker/Flyspray - How and When to use it" (tab Forum) is giving some hints.
  
• To see what version you are using either look in ?->about or at the top of your display. A lot of information is also available in the log file. See below.
  
  

Location of Important Files. Log and config files.

• It is important to know the location of the log file and the configuration file, opencpn.conf(Linux) or opencpn.ini (Windows), on your computer. If you ask questions on the forum, there is a fair chance that you will be asked about the content in these files. Once you get familiar with OpenCPN, have a look at the files!
• Through out this documentation there will be many references to the configuration file, as it often is possible to change the default settings. This is an advanced subject once you are familiar with OpenCPN. All editing in the config files must be done with a text-editor, such as "notepad" in Windows.
• The configuration file is where all data, that needs to be persistent between sessions, are stored. The logfile keeps tab of what's going on in the current session.
• To find the locations of the files go to the ToolBar click on "About OpenCPN", the button looks like a blue book with a "?" on the cover. Look at the bottom of the "About" Tab, highlighted below. The illustration below is from a Win XP. A quick way to view the logfile is to copy the full file path and then paste this into the address field in a web browser.
  
  
• For quick copying of the opencpn.ini and Log files use the two "Copy" buttons. This is useful for publishing on the forum if asked to do so. Please use the Forum "Code" button before pasting, as this guarantees an exact copy.
• On Linux the "opencpn.log" is in your home directory.
  The "opencpn.conf" is in a hidden directory, called "opencpn", also in your home directory.
  For a quick way to view the files you can try these commands.
  $gedit `echo $HOME/opencpn.log`
  $gedit `echo $HOME/.opencpn/opencpn.conf`
  Of course you can swap "gedit" for your favorite editor.
• On Windows 7, Windows 2000, XP and Vista the two files are more difficult to find, so use the "About" dialog as described above. On many windows installs the folder containing the logfile will also be hidden, so you need to change your systems "Folder Options" to show it.

For example, the C:\ProgramData folder is by default hidden in Windows 7. Here's how to get to it:

To access it you need to un-hide it by doing the following:

1. Go to Control Panel > Folder Options
2. Switch to View tab
3. Select "Show hidden files, folders and drives".
4. Unselect "Hide extensions for know file types" to get this state:

Now you will be able to find your logfile.

• On Mac OS X, the logfile, "opencpn.log", is in /Users/"user name"/Library/Logs/ and the "opencpn.ini" is in the /Users/"user name"/Library/Preferences/ directory.

If something goes wrong

• If you have installed OpenCPN successfully and later run into trouble there is generally no point in reinstalling. It is a very common reaction among users, but achieves very little.
• If openCPN refuses to start, or hangs after the introduction dialog and you have Intel integrated graphics on your computer, try to start the program from the command-line with -> "opencpn -no_opengl"
• Still no luck? Proceed by checking your logfile and try to find a hint there.
• Next step is to close down OpenCPN, if it's still running. Then save any possibly valuable data. Read about Navigation Data Backup
• Proceed by renaming the configuration file - opencpn.ini to , for example, opencpn_OLD.ini. When you start OpenCPN again it will be like a new install, no chart directories and all settings are default.
• If you still have problems, and especially if your log file complains about navobj.xml files, close down OpenCPN and move all navobj.xml files to another directory. Rename the opencpn.ini file again, and then restart as before. If successful, close down again, and try to move, first the navobj.xml.1 back to the original directory renaming it navobj.xml. If not successful, try navobj.xml.2 etc This last step is only necessary if you have valuable data that's not saved elsewhere.
• If this is successful, please post your old config file and your original navobj.xml file, together with full information of what happened, and your system, on the Cruisers Forum. To do this, first rename the file by adding ".doc" to the end of the file name.
• This will help the OpenCPN developers to understand what's going on.
• Still having trouble? There is a lot of info available on the forum. Use the search function to see if your problem is already solved.
• No luck? Post a question to the Forum. Please include as much info as possible, as this will speed up the process and help other users to help you. Include the following:

1. Your Hardware and operating system, including versions.
2. Which version of OpenCPN, or plugin version.
3. A full description of your problem.
4. If possible, also include the opencpn.log and screen dumps showing your problem.

OpenGL

What is OpenGL an Overview
OpenGL is an open standard, cross platform, advanced graphic library. It uses the graphic cards processor (GPU) and memory, to speed up applications. With OpenCPN a user with a typical modern graphic card will have an enhanced experience. Much faster and smoother zooming and panning as well as clearer and sharper chart rendering.

In OpenCPN OpenGL is a choice, the old graphic engine is still there. OpenGL will not work for everyone. Performance may not be improved with embedded graphics chips, often found in older laptops and netbooks.

Microsoft has gone from support to hostility towards OpenGL. There is currently a lot of trouble Windows for all OpenGL applications, not just OpenCPN. OpenCPN has been forced to disable a handfull of OpenGL features for all Intel OpenGL graphics drivers on Windows, for example.


Mac OS X has full supports for OpenGL.

For Linux the situation is slightly different. Linux supports OpenGL, as it generally tends to support open standards. The user is however dependent on a driver from the graphic cards maker, and their support for OpenGL. This may change with projects like nouveau, a free driver for nVidias cards.


Without OpenGL With OpenGL
Heavy over zooming reveals some of the secrets behind OpenGL

Why introduce OpenGL in OpenCPN?
The main reasons are:

• Better performance, leveraging modern PC graphics cards that are ubiquitous and powerful.
• Better "eye candy", such as smooth zoom and pan, with little impact on responsiveness.
• Future cross-platform support (e.g Android/IOS)
• Some features depends on OpenGL, such as horizontal text and numbers on skewed (course up) vectorcharts.

Is OpenGL a good choice for everyone?
OpenCPNs performance with OpenGL is highly dependent upon your graphics hardware and drivers.

• On some systems using Intel HD Graphics adapters, especially running 64bit editions of Windows 7, OpenCPN gets killed due to errors in the display adapter drivers. You may try to get updated drivers or as a workaround, on Windows run OpenCPN - no OpenGL from Start menu. On all the platforms, you can use the -no_opengl command line switch while starting the program to run it with OpenGL disabled.
• Some graphics chip sets (e.g.intel 945G) have rather poor OpenGL driver support, so that we cannot fully utilize the hardware acceleration potential of these systems.
• nVidia graphics, even very old cards, seem to perform very well.
• Performance may not be improved with embedded graphics chips as often found in older laptops and netbooks.
• There is a lot of trouble with OpenGL on Vista and W7. Microsoft implemented a new screen compositing model for Vista and later, which "broke" many OpenGL apps
• Conclusion:Using OpenGL with OpenCPN will be a significant upgrade for some users of OpenCPN, but OpenGL may not be "better" for everyone's OCPN application.
• So, user's choice. If OpenGL works better for you, then use it. If not, the old DC based graphics render system is still in place.

Start using OpenGL

• Find the latest driver for your graphic card. The driver that came with your operating system, is not likely to be the best. Start looking at your graphic card makers home page.
• Go to the ToolBox->Settings and tick the two boxes "Use Accelerated Graphics(OpenGL)" and "Enable Smooth Panning/Zooming". Read all the details in the Setting Options display tab.

Other tricks
If you have a lot of graphic memory, or very little, try to add the following to your config (ini on windows) file:
"GPUMemorySize=nnn"
where nnn is graphics card memory size, in MBytes.
256 MBytes is the default.

Go to Table Of Contents

Low Power Systems

This is an advanced subject. Beginners need only bother, if they have a system with very low resources and if the system feels very sluggish. The background is that OpenCPN, quite aggressively uses memory, to speed up the application, this can backfire in certain situations....

There is a simple memory management scheme, for use with systems that has limited resources.
Two modes are available, only one of which can be active at any given time. The mode must be specified in the "opencpn.conf" file, called "opencpn.ini" in Windows and Mac.

1. Application memory limit target. Try to limit the total memory used by OCPN to the specified value, approximately.
Specify this mode by:
......
[Settings]
MEMCacheLimit=xxx
......
Where xxx is memory use target in Mbytes. Overrides NCacheLimit below.

2. Open chart limit. This is the default mode under Linux, and the default value is 20 open charts at any one time.

Modify this limit by the following:
......
[Settings]
NCacheLimit=yy
......
Where yy is the maximum number of simultaneously open charts.

If you do not enter any memory management specification in the config file, the following defaults apply:

a. Linux systems has a soft memory limit at 50% of available RAM. Open chart limit is 20 charts.
b. Windows and Mac...Application memory limit target is used. Target limit is 50% of available physical RAM, up to a maximum of 1 gigabyte.

Settings for increased speed.

In Options->Display-Advanced tab activate "Disable Full Screen Quilting" to start with. Use OpenGL if your hardware is up to it. If you are using OpenGL on a low-spec machine, you will have better performance if you
a) disable texture caching, or
b) Pre-build the texture cache in a region of interest. That is, move the boat to say Dover. Then do Options->Advanced>(OpenGL)Options->Build Texture Cache. You do not need to wait the entire time, which may be hours for a large chart set. "Skip" out when the distance reported is 100 miles or so.
Eventually, after steady use, your texture cache will be filled automatically in the background, and performance will increase steadily.


Go to Table Of Contents

Portable OpenCPN

The OpenCPN portable option allows the program to run from an USB stick, or run independent from, and parallel to a normal installation. On Windows, it is not possible to run concurrent instances of OpenCPN, unless using the portable option.
To differ between various instances of the program, the titlebar on portable versions looks like this.

It is thus possible to run multiple portable instances and identify each version.

To create a portable Windows version (across only 32-bit or only 64-bit systems)

1. Create a new directory dedicated to the portable OpenCPN.

2. In a separate window, navigate to C:\Program Files (x86)\OpenCPN (on 64-bit systems) or C:\Program Files\OpenCPN (on 32-bit systems), and copy (don't move) the following data directories (with containing files) into this new direcory:

• doc/
• plugins/
• s57data/
• share/
• sounds/
• tcdata/
• uidata/
• wvsdata/ (only for OpenCPN 3.2.0 and earlier)

3. From the same OpenCPN folder, copy the following files into the new directory:

• crashrpt_lang.ini
• CrashRpt1401.dll
• CrashSender1401.exe
• license.txt
• OpenCPN.exe (of course)
• Eight wxWidgets dlls beginning with the name "wxbase"

4. Now navigate to C:\Windows\SysWOW64 (on 64-bit systems) or C:\Windows\System32 (on 32-bit systems) and copy the following files into the new directory:

• msvcp100.dll
• msvcr100.dll

5. If running Windows, create MSDOS batch file "opencpn portable.bat" (or other name of user choice) containing the one line:

"opencpn -p" (without quotes)

This file must be in the new directory. If you want your batch file to be in a different directory, you must edit the batch file to include "cd" commands to navigate into the new directory before the line containing the "opencpn -p" command.

To run OpenCPN portably within this directory, simply execute the "opencpn portable" batch file. There may be a way to build a click-able shortcut to OpenCPN, with the -p option specified in the shortcut. But I could not figure it out. Windows insists upon a drive letter in the command line of the shortcut, which would defeat the whole purpose of portability.Thus, the batch file....

If the charts are also in the current dir, then the entire installation is "portable", meaning there are no hard-coded drive letter dependencies, and all write activities occur in the current dir only.

This setup works very well from a USB stick.

Alternate procedure to use the 64-bit libraries upon demand

The setup described above will work on 32- or 64-bit systems, as long as you are careful to copy msvcp100.dll and msvcr100.dll from the exact folders that were specified. Those files are 32-bit libraries, which will run without problems on both 32- and 64-bit systems.

If you accidentally copied the 64-bit msvc*100.dll library files (which are located in C:\Windows\System32 on 64-bit systems) a 32-bit system, you will get an error message when trying to run in portable mode. If you want cross-compatibility between 32- and 64-bit systems, it is strongly suggested to use the 32-bit libraries described in step 4 above.

If you insist on using 64-bit libraries on 64-bit systems, but want to preserve 32-bit compatibility on 32-bit systems, you can do the following setup procedure which creates separate batch files for the 32-bit and 64-bit versions of msvcr100.dll and msvcp100.dll in the OpenCPN root directory as described here:

1. Same as above
2. Same as above
3. Same as above

4. Create MSDOS batch files "opencpn portable 32.bat" and "opencpn portable 64.bat" (or other names of user choice that distinguish between the 32-bit and 64-bit operating systems).

In the MSDOS batch file "opencpn portable 32.bat", add the following lines (without quotes):
"copy msvcp100_32bit.dll msvcp100.dll /Y"
"copy msvcr100_32bit.dll msvcr100.dll /Y"
"opencpn -p"

In the MSDOS batch file "opencpn portable 64.bat", add the following lines (without quotes):
"copy msvcp100_64bit.dll msvcp100.dll /Y"
"copy msvcr100_64bit.dll msvcr100.dll /Y"
"opencpn -p"

5. Copy msvcp100.dll from the 32-bit system and rename it msvcp100_32bit.dll
Copy msvcr100.dll from the 32-bit system and rename it msvcr100_32bit.dll

6. Copy msvcp100.dll from the 64-bit system and rename it msvcp100_64bit.dll
Copy msvcr100.dll from the 64-bit system and rename it msvcr100_64bit.dll

To run OpenCPN portably on a Windows 32-bit system, execute the "opencpn portable 32" batch file.
To run OpenCPN portably on a Windows 64-bit system, execute the "opencpn portable 64" batch file.

If you want to give a higher running priority see : http://opencpn.org/ocpn/commandline

A Linux version

On Linux, a similar functionality exists. The 32 and 64 bits issue is similar.
32 bits version can be made to work on a 64 bits Linux by installing ia32-libs or multiarch support packages. The opposit way, a 64 bit version on a 32 bit system, will not work.
Copy the opencpn executable binary and the data directories mentioned above to a local directory.
In that directory, do
$ ./opencpn -p
This will cause all user data files to be created and used from within that local directory.
This can be useful for side-by-side testing...

Go to Table Of Contents

Using OpenCPN for the First Time

Setting Up GPS

Windows 98/ME/2000/XP/Vista/7

To use OpenCPN with a GPS, a GPS receiver is needed.

There are a variety of possible choices for a GPS receiver:

• A computer, such as a Sony Vaio P has a built in GPS receiver
• A NMEA Expander to amplify a nmea stream to multiple listeners
• A hand-held GPS receiver
• A dedicated GPS receiver

The remainder of this section describes using OpenCPN with a dedicated GPS receiver, however, the instructions for a dedicated receiver will be similar for any serial/USB connected NMEA data stream.

A Dedicated GPS Receiver

There are several companies making dedicated GPS receivers. The Supplementary Hardware section for GPS devices lists several manufacturers.

NMEA has traditionally been implemented as a serial protocol and therefore, even if a USB connection is used, there needs to be a USB to Serial Port conversion. The specific driver for the each GPS receiver will handle this conversion.

An Example - Configuring BU-353

It is not necessary to use the installation disk to setup the BU-353. Following the steps listed below will result in the latest driver being installed.

1. Download the latest driver from Prolific - http://www.usglobalsat.com/s-24-support-drivers.aspx#A
2. Unzip and install the driver
3. Plug in the BU-353.
4. Start -> (Right Click) My Computer -> Properties -> Hardware ->Device Manager
   or Start->Run devmgmt.msc
5. Expand Ports
6. Look for the “Prolific USB-to-Serial Comm Port” and note the com port number (e.g., COM4)
8. Right click on the “Prolific USB-to-Serial Comm Port”. Choose Driver
9. Select 4800 bits per second, 8 data bits, None parity, 1 stop bit, and None for Flow Control
11. Start OpenCPN
12. Click on the Options Icon
13. Select "Connections", and "Add Connection" and "Serial"
14. Under "Data Port" select the Com port noted in #6
15. Choose OK
16. Select Auto Follow to center the map over your GPS location

Troubleshooting

There is a small LED located on the BU-353. If the LED is off there is no power being received. Check the connection.

If the LED is solid it indicates the BU-353 is searching for a GPS signal. Try moving the GPS receiver to a clear location.

If the LED is flashing it indicates the BU-353 has a position fix and is transmitting data.

1. Try viewing the NMEA data stream in OpenCPN. Choose Options->Connections->Show NMEA Debug Window
2. Alternatively, a diagnostic program is included on the installation CD called GPSInfo.exe. Launch this program to install the diagnostic utility.

If it appears that the NMEA data stream is being received, the most likely issue is that OpenCPN is not centered over your location. Click AutoFollow to center the map at your GPS location.

Known Issues

If you change the USB port for the GPS receiver Prolific will reassign the COM port number. This will require repeating steps 4-12 above.

On some computer / GPS receiver combinations when the computer resumes from Stand By the GPS receiver will no longer transmit its NMEA data stream, and only garbage instead of ASCII characters will be visible in the NMEA Data Stream Window. The red indicator led will not work.

To change back to NMEA mode search for and download SIRFDemo.exe.
Unpack and start. Set correct Baud rate and and com port as above.
Click connect to data source button. Action -> Switch to NMEA protocol, then exit.
There are many more settings available in SIRFDemo.exe

An alternative workaround for this issue is provided by using a COM port splitter such as XPort http://curioustech.home.insightbb.com/xport.html

1. Download XPort.
2. Unzip it to a folder of your choice
3. Double Click XPort.exe
4. Set the Baud Rate to 4800
5. Under Enable Ports add an entry for COM10
6. Click “Find GPS”. The port returned should match the port identified in Step #6 in the Configuring BU-353 Section
7. Select Prolific USB-to-Serial Comm Port in the check box section
8. Return to OpenCPN
9. Click on the ToolBox Icon
10. Select GPS

Linux

To proceed, the "user" you use on your computer must belong to a group that is allowed to open serial connections. This group is normally "dialout" on Debian based Linuxes, including Ubuntu, and "uucp" on Red Hat based distributions. Read more in Data Connections.
Check your status by writing "groups" on a command line. The response will be all groups that the user belongs to. Make sure that "dialout" or "uucp" is included. If not, you have to add your user to this group. There are many ways to do this, one is to issue this command:
"sudo usermod -a -G dialout $USER"
This applies to many Debian based distibutions, for other distros just drop the sudo and do the command as root, using "su".
All major Linux distribution includes a graphical user settings dialog, where adding a user to a group, could be fixed.

Two methods are available, direct connection or through gpsd.

We start with gpsd.

• Install the gpsd and gpsd-clients packages
  • $ sudo apt-get install gpsd gpsd-clients
• Go to Options-> Connections-> Add Conection and select "Network" plus the GPSD radio button. Address should be "localhost" and DataPorts should be set to 2947.
• On Ubuntu 10.04 and later, that is really all you have to do. When you plug in your gps this will trigger gpsd to start.
• "xgps" is client that comes with the gpsd-clients package, and is useful for testing that the gps and gpsd is working properly. If xgps isn't working, it's a gps or gpsd problem, not an OpenCPN problem

Direct connection.

• Make sure that gpsd isn't running then connect your gps and start OpenCPN. On Ubuntu 12.04 the easiest way to achive this is to unistall gpsd.
• In the Options->Connections -> Add Conection, select "Serial".Set "dataPort to the port where you plugged in your gps. If you plugged in BU 353 this will probably be /dev/ttyUSB0.
• Choose 4800 baud, unless you know that the gps is set to something else.
• The gps should now work....if not, check the NMEA data stream window. If only binary garbage is visible, the gps has to be reset to NMEA mode, see more about this above in windows section. An alternative is to use gpsd, that will work with the gps in Sirf mode.
• To do this in Linux for BU 353 as well as many other gps:es, make sure that gpsd is running and that the package "gpsd-clients" is installed. On Ubuntu 12.04 gpsd needs to be temporarily installed. Make sure to kill any instances of gpsd with the command "sudo killall gpsd"
• The command $gpsctl -n will put the GPS into NMEA mode.
• If that doesn't work, try $ gpsctl -f -n /dev/ttyUSB0 .This will force a low-level access, bypassing gpsd. For more information: $man gpsctl
• More information is as always available through "man gpsctl" Close down OpenCPN before running gpsctl.
  
  None of this is normally noticed when using gpsd, as this program reads both NMEA and SIRF binary sentences.

• More Linux hints

• If you can't connect to a physical port, such as /dev/ttyUSBO, indicated by a line in the opencpn.log file. Check that you, as a user, belongs to the group "dialout". To see which groups you belong to, run the command "groups". Not all Linux distributions add the user to this group by default. To add your self to the dialout group -> "sudo usermod -a -G dialout $USER"
• Check if gpsd is working:
  $ ps aux | grep gpsd
  nobody 12338 0.3 0.1 4124 1448 ? S<s 18:31 0:00 gpsd -F /var/run/gpsd.sock
  you 12356 0.0 0.0 3036 800 pts/3 S+ 18:32 0:00 grep --color=tty -d skip gpsd
  This or similar responses indicate that gpsd is running. If you only have something like the second line, ....it is not running.
• Run the command "$ls -lrtd /dev/*|tail -10", and see the 10 latest created device files. Run this just after plugin in your gps to see which device was created.
  
• Determine which device your GPS is on your linux system by checking the startup. Look for a line that says something about GPS and /dev/ttyUSB# in the command "dmesg"
• Or even better, after connecting a gps mouse, BU-353, we look for a dmesg by running this command.

  $ dmesg | grep tty
  and get this response back.
  [13616.095305] usb 2-3: pl2303 converter now attached to ttyUSB0
  
  

• Add a script to start gpsd, if this is not done by your distribution. I saved mine as startgps and set the executable attribute. Edit line 3 to match your device, ie /dev/ttyUSB0

  • #!/bin/sh
     sudo killall gpsd
     sudo gpsd -n -D 2 /dev/ttyUSB0
     

• Run the script:

  • $ ./startgps

Other Distributions

• Install gpsd from source. More information is available here: http://catb.org/gpsd/

Udev Rules

• If you have problem with, for example gps, connecting to different ports each time you restart udev is your friend.
• udev supports persistent device naming, which does not depend on, for example, the order in which the devices are plugged into the system. The default udev setup provides persistent names for storage devices.
• There is a lot about udev on the Internet. For OpenCPN specifics, read this post:Udev in 2.5

Bluetooth GPS

Ubuntu 10.10 and older.

	#
	# RFCOMM configuration file.
	#
	# $Id: rfcomm.conf,v 1.1 2002/10/07 05:58:18 maxk Exp $
	#

	rfcomm0 {
	        # Automatically bind the device at startup
	        bind yes;

	        # Bluetooth address of the device
	        device xx:xx:xx:xx:xx:xx;

	        # RFCOMM channel for the connection
	        channel 1;#use channel number as provided by sdptool records XX:XX:XX:XX:XX:XX

	        # Description of the connection
	        comment "Your GPS Device Here";
	}

Fedora

Mac OSX

Touch Screens and Tablets

Help the Developers Fixing Bugs!

If you experience a crash in OpenCPN, the developers are very keen on knowing why. This is how you can help making OpenCPN, even better.

Windows

In OpenCPN ver 4.0 the semi-automatic Crash reporting for Windows is disabled by default.
Crash Reports are saved in the OpenCPN config directory, i.e. where the log file is stored now. End users may occasionally be asked privately to send these reports to a designated recipient.

The semi-automatic Crash reporting can be enabled by editing the opencpn.ini file.
--
[Settings]
.....
EmailCrashReport=1
---
Here is what you will see if OpenCPN causes a crash with the crashreport enabled.



Provide additional information, such as your email or forum name, so the developers can contact you for more info, if necessary.



This is what the report will contain. Use the "Export" button if yoy don't have an Internet connection at the time of the crash. Mail the report later.

Also, for fun, you may test this option by the keystroke Alt-F12. This will induce a benign crash, and give you a chance to see what it will look like before the real thing happens. Please don't send this kind of report by pressing "Send report". Just press "Close the program" when you are done. Restart OpenCPN! This feature is temporary and will not be available in the Beta Release following 3.3.814.

Linux

In Linux there is an excellent tool, "ddd", the Data Display Debugger, to help the developers pinpoint where an error, or bug, is located in the source code. "ddd" is a graphical front-end to the text based "gdb", the GNU debugger.

Install ddd through Synaptic, Ubuntu Software Center or similar for other Linux distributions.
From a command line, in a Debian based Linux, such as Ubuntu, issue this command:
$sudo apt-get install ddd

• The "$" sign above, just marks that this is a command line for a normal user. Do not include it in the actual command. This is a Linux convention used everywhere.

Start ddd

To start ddd, find a command-line and
$ddd opencpn

ddd starts and this is what you will see.



Click "Run". If you don't get this small dialog, go to Program -> Run, or hit F2
This will start OpenCPN. Just continue in OpenCPN and proceed to create a crash.
Then go back to the ddd window.
This is how it will look like after a crash.



Notice "Program received signal SIGSEGV, Segmentation fault."
This is programmers way of saying a "crash". Exactly what this means, does not matter for a normal user. Interested anyway? Read more, http://en.wikipedia.org/wiki/Segmentation_fault
To actually help the developers we need a back trace from the crash. This is the path that the program followed in the source code, leading to the crash.


Go to Status -> Backtrace.
This is what comes up, from this particular crash.


The crash happened at #0 and this very short back trace started at #9.
Your job now is to take a screen-dump, similar to the picture above, and send it on.
Try to get as much of the back trace as possible, by expanding the Back trace dialog.
This is important, so the developers can see the trouble point in the source code.
Look at #3 above, ending in "....chart1.cpp:2367". "chart1.cpp" is a part of the OpenCPN source code, and something on line 2367 was involved, directly or indirectly in the crash.
Lines ending in "......... .so.0" are external libraries used to run OpenCPN.

On the odd occasion, when the back trace is very long, the developers may still complain that they need to see more.

Using gdb

Gdb, the command line debugger, is the answer.
Start like this
$gdb opencpn
Gdb starts and you get the gdb command prompt (gdb).
Just type "r", for run and hit Enter. Like this:
(gdb) r

OpenCPN will now start, once again, make it crash.
The console will look similar to below.


All the lines before the "Segmentation fault" line, are just "chatter" from PortAudio and Gdk, and are not directly related to OpenCPN.

To get a back trace, simply
(gdb)bt
That is type "bt", for back trace, and hit enter.



You will now have access to the full back trace, with more details and reverse order to "ddd".
Copy the text, and send it on.
Press "q" to exit gdb.

Send it on to the Programmers
Tell the programmers about your findings through an entry in the tracker http://www.opencpn.org/flyspray/ , or through posting on the forum http://www.cruisersforum.com/forums/f134 , if you have found a new bug.


Go to Table Of Contents

The Menu Bar

Navigate

Toolbar Buttons

The Toolbar is floating and can be placed anywhere on the screen, vertical or horizontal.
Note the "grabber" symbol at the far right side of the toolbar. Use this handle to drag the toolbar wherever you want it. The default position is horizontal and docked top left.
It "snaps" to the edges. Right click on the grabber, and the toolbar shifts to vertical format. On Windows (at least), unless in OpenGL display mode, the toolbar dims down transparently until you roll over it.

There are three different styles of Toolbars to choose from. Go to the ToolBox->"User interface"-> "Toolbar and Window Style" and select one of the following styles:

Traditional

Journeyman

Journeyman Flat

There are a lot of buttons available in the standard Toolbar, even more, counting the many plugins. To control exactly which buttons to display, hold the cursor over any button and right-click. This dialog pops up.



Only the buttons with a ticked box will be displayed. The available shortcuts are also shown in parenthesis to the right of the button description.
The MOB button is special. If unticked, you will get these choices:



#1: The MOB button will still be there, but anyone (crew?) may later hide it.

#2: If OpenCPN is used to handle a MOB situation, choose this option. The MOB button will always be there. It is not possible to change the state as long as OpenCPN is running. The MOB button option will not even appear in the right-click menu.
To reset this option open the opencpn.ini(config) file and change the value below from
"1" to "0". Restart and all the options are once again available.
"[Settings]
....
PermanentMOBIcon=1"

#3: Use this option if a MOB situation is handled by other means, and OpenCPN is not a part of the standard operational MOB procedure.

If the MOB button is visible, it will always be the button furthest to the right. This way it's always easy to find in bad light etc.

The visibility of the plugin buttons is controlled in the ToolBox->Plugins Tab, by pressing the Enable/Disable toggle button.

Note that the Toolbar must have at least one active button.




When a toggle button is pressed, it changes and becomes darker, Traditional style also adds a stronger outer frame. For example, tracking off , tracking on .

A brief explanation of the use of each button is available by just hovering with the cursor

over a button.

Traditional Style (from left to right) :
(For translation to other styles, check the buttons just below the Traditional in the above pictures.)

Zoom In (Zooming)

Zoom Out (Zooming)not

Scale Next Chart Down (Scaling Charts) ¹

Scale Next Chart Up (Scaling Charts) ¹
Create Route (Marks and Routes)

Find/Follow Boat. Toggles on/off.(Auto Follow and Display Orientation)

Launch Toolbox(Setting Options)

Show/Hide Text Labels on Vector Chart.(Vector Charts)

Show/Hide AIS Targets ² (AIS)

Show/Hide Currents On Chart (Tides and Currents)

Show/Hide Tides On Chart (Tides and Currents)

Print. Prints your current view, using a simple dialog.

Route/Track/Waypoints/Layer- Manager.(The Route Manager and Gpx Data )

Toggle Track On/Off (Ship Track)

Adjust Screen Brightness for Dawn/Dusk and Night viewing.(Night Navigation)

Drop Man Over Board marker(Man Over Board) Always the far right Button.

About OpenCPN and Help File (Getting Started)
Show/Hide the Dashboard Plugin (Dashboard Plugin)
Show/Hide the Grib Overlay Plugin (Grib Weather Plugin)

A separate GPS status and Chart Orientation Status is normally in the upper right corner of the display, unless the floating ToolBar covers this position. Then the "Staus-bar" will be moved to the lower left corner, were it will stay, unless the main ToolBar iis moved to cover this position, in which case the "Status Bar" goes back to the default position.

Course Up/North Up ² (Auto Follow and Display Orientation)

Go to Table Of Contents

Right Click Menu

The basic single charts right-click menus.

Measure

Max Detail Here

Scale In

Scale Out

Move Boat Here

Course Up Mode

Object Query

The basic quilted charts right-click menus, for raster charts and vector charts

The only new item in the quilted menus is

Keyboard Shortcuts

The List sorted by Keys

Function Keys

• F2 toggle Auto Follow on / off
• F3 toggle ENC Text.
• F4 activates the chart measure pencil. Esc Stops it
• F5 toggle Daylight, Dusk & Night mode, if built into the Chart ( "C", Ctrl+C, Ctrl+G)
• F6 General Dimming, in steps, of the entire Screen. (except Mac OS X ) OpenGL must be off.
• F7 Larger Scale Raster Chart (Scale In) or Ctrl + Left-Arrow
• F8 Smaller Scale Raster Chart (Scale Out) or Ctrl + Right-Arrow
• F9 Chart Quilting . Toggle on/off
• F11 toggle Full Screen view.
• F12 toggle Chart Outlines
• SHIFT + F6 reverses the dimming.

• C change color scheme -new similar to Ctrl+C, Ctrl+G and F5
• L toggle Vector ENC Lights on/off. "Mariners Standard" display category.
• O toggle Chart Outlines. or F12
• T toggle ENC Text or F3
• S toggle ENC soundings.
• A toggle bottom features, useful when anchoring. "Mariners Standard" display category.
• D toggle CM93 Detail Slider. Hide only works, if the slider lost focus.
• M toggle Measure Tool F4
• Q toggle Chart Quilting
• + Zoom In
• - Zoom Out

• Alt. Toggles Menu Bar on/off of Show menu is not checked.
• Alt + Arrow Keys. Moves the chart view in very small steps.
• Alt + "+" for fine scale zooming in.
• Alt + "-" for fine scale zooming out.

• Ctrl + Space Man Over Board, sets MOB Marker at current GPS position.
• Ctrl + scroll wheel, zooming in/out in small steps
• Ctrl + Left-Arrow-Key Larger Scale Chart (Scale In) (F7)
• Ctrl + Right-Arrow-Key Smaller Scale Chart (Scale Out) (F8)
• Ctrl + B toggle the Chart Bar.
• Ctrl + C Change color scheme - new similar to Ctrl+G, "C" and (F5)
• Ctrl + G* cycles through green, red and normal screen.
• Ctrl + I toggle small dialog, containing GPS status & Course/Up North Up Icons, on/off.
• Ctrl + M Drops Marker at current cursor position.
• Ctrl + N Activate next waypoint in an active route.
• Ctrl + O Drops Marker at current owship position.
• Ctrl + Q Quits OpenCPN
• Ctrl + R Starts the Routing tool. Esc ends creating route.
• Ctrl + Y Redo Mark/waypoint create, move or delete.
• Ctrl + Z Undo Mark/waypoint create, move or delete.
• Ctrl + , the option Window is displayed

• Keyboard Arrow Keys. Moves the chart view.
• Left clicking on a chart, centers the chart on that point.
• Double clicking a vector chart, displays all info for that point (exception below).
• When the cursor becomes a green arrow, clicking pans in the direction od the arrow.
• Double clicking on an AIS target, displays the target query dialog.
• Double clicking on a mark or waypoint, displays the Mark Properties Dialog
• Double clicking on a route or track, displays the Route/Track Properties Dialog
• Right clicking on any chart, access a context sensitive menu.
• Esc ends the process of route creation or stops the measure pencil.
• Right Mouse click on chart View center lat & long
• Left Mouse click on chart moves to center of view
  

• Scroll Wheel, zooming in/out
• Alt + scroll wheel, zooming in/out in small steps.

• When the cursor becomes a green arrow, clicking pans in the direction of the arrow.

* Ctrl-G Works on some Windows systems (depending on graphic driver).

NOTE: This list may not be completely detailed and correct for now, but it does try to establish all the shortcuts available.
We may need to add some things to Caesar's Functional and tabular list to make it more complete. Please contribute ideas and corrections/improvements!

Zooming

It is essential to understand what happens when both zooming in and zooming out in a chart view. Vector charts have their own issues, with both over- and under- zooming. Both can be potentially dangerous, and it's essential to understand what's going on.

How too Zoom in/out

These buttons allow you to zoom in and out on the chart currently being displayed.

Will zoom the chart in for more detail, larger scale.

Will zoom the chart view out for more area, smaller scale.

Alternatively, the + and - keys on your keyboard will zoom in and out. If you have a mouse with a scroll wheel, it can also be used to quickly zoom in and out.

Other alternatives for zooming includes:

• Page Up for zooming in.
• Page Down for zooming
• Menu Bar->Navigate click Zoom In / Zoom Out

• Alt + for fine scale zooming in.
• Alt - for fine scale zooming out.
• Alt + scroll wheel, zooming in/out in small steps.

Some settings for zooming are available in the Options -> Display->General tab. Read more about "Smooth Panning/Zooming" and "Zoom to Cursor" in Setting Options .

Note that

• Keyboard, Menubar, and Toolbar zooms always zoom to the center of the screen.
• Wheel zoom behaviour changes depending on "Zoom To Cursor" and "SmoothZoom" settings.

Overzooming

Overzooming settings are explained in Setting Options . In short OpenCPN, by default, blurs vector-charts and expands the text an lines, to imitate what happens with raster charts, when zooming in beyond a factor 10.0 x .

Unlimited zooming is available using the background Map. Just create an empty chartgroup and switch to this map at any time. More in Chart Groups.

Underzooming

Using CM93 in OpenCPN

All About Charts

Installing Charts
Status Bar
Chart Info
Scaling Charts
Chart Quilting
Chart Groups
Vector Charts
S63 Vector Charts
Chart Formats
Chart Sources

Installing Charts

The potential danger to the mariner increases with digital charts because by zooming in, he can increase the chart scale beyond what can be supported by the source data. The constant and automatic update of the vessel’s position on the chart display can give the navigator a false sense of security, causing him to rely on the accuracy of a chart when the source data from which the chart was compiled cannot support the scale of the chart displayed. Bowditch 2002 Ed p 412.

Brazilian charts - a free download.

OpenCPN does not come with any pre-installed charts. It is up to the user to find and install charts. Read on, and you will find detailed information about which chart formats that OpenCPN can display, as well as pointers to all available charts for OpenCPN, free downloads as well as commercial, that we know of.

Background Chart. OpenCPN comes with a worldwide background map, displayed if no charts are available for an area.



To install charts, OpenCPN must be pointed to a directory containing Charts of one of the recognized Chart Formats. Don't point OpenCPN to individual charts. You must specify the directory that contains the charts.

Where do I keep my charts ?
The installation tells you to go to the Options->Charts->Chart Files tab to install charts.
When you press the "Add Directory" button the default directory will be "My Documents" for Windows, and the users home directory, for Linux and Mac. These are good places to keep your charts. Create a "Chart" directory, and maybe some sub directories, to keep your charts in, and you can't go far wrong.
Seasoned users knows where they want their charts.
Regard charts as data, independent of OpenCPN. Store them in a place that is convenient for you and that is left alone by the operating system.
Download some charts (see Chart Sources) to your newly created Chart directory. Follow the directions below to make this directory an "Active Chart Directory"

The main consideration for charts is storing them in a directory where they will not be tampered with or moved accidentally.

Installing Charts
Open the Options Dialog by clicking . You are sent to the first tab "Display". Tick the box "Show Chart Outlines". That will help you visualize the loaded charts.



Then click the tab "Charts" and then the tab "Chart Files".



There are no charts loaded. To add charts we have to add a directory that contains charts of a recognized format. To get started press "Add Directories" and navigate to your chart-directory.



Exactly how the dialog looks like depends on your operating system, and is not a part of the core OpenCPN.
When clicking the button "Open" above, the highlighted chart directory is added to the box "Directories". The screen-shots are from Linux, but this process works similarly on all platforms. Add more chart directories using the same process again. It's OK to load both raster- and vector-charts together.



All that remains is to click the "Apply" button. OpenCPN will then process your selection. You can now start using your charts. When you are done with your settings click "OK" and the Options Dialog closes. If you are just adding a chart directory, it works fine to just click the "Ok" button.

The charts often come in a compressed package eg. a ZIP archive. You must first uncompress them to your disk to be able to set them up. The following screenshot shows the file and directory structure of the NOAA raster charts (RNC) on a local disk



Note that in OpenCPN you must add directories (folders) containing charts, not the individual charts.

For BSB4 and nv-charts, first install the latest plugin version, then point OpenCPN to the correct chart directories and finally do a "Full Database Rebuild".

Eager to get some charts quickly, to get started? Go to: Chart Sources

Check your charts after installation

This step is important if you just installed some old BSB charts, say from the ninties, or charts of dubious origin. For example, there are a lot of old Maptech charts that uses the Geodetic Datum "Unknown".
It is not a problem with recent charts.
OpenCPN Version 4.0 will reject charts without a projection and add a note in the log about the problem.
Charts with an unrecognized Geodetic Chart Datum will be loaded as if they were WGS84. This may lead to unacceptable errors. The Chart Information Dialog will contain the sentence:"Warning: Chart Datum may be incorrect." , and the log will contain a note with the words "Chart datum {XXXX} invalid on chart".
For practical use, it's very important that the implication of this is understood.
Read up on the subject in the Chart Info page

Start using your charts.
You can click and drag the chart with your mouse. The cursor changes to an triangular green arrow near the edges of the OpenCPN window, left clicking in this situation, pans the chart in the direction of the arrow. The scroll wheel zooms in and out. Left clicking anywhere centers the view on that position. Right clicking brings up a menu with useful actions. Exactly what the menu contains depends on the circumstances. Read the rest of the manual for a full explanation.

If you are running OpenCPN for the first time you may see the background chart instead of the charts you installed. That simply means OpenCPN is pointed at a location that is not on any of the charts you installed. Click and drag, or use the arrow keys, to move the view-point to the location of one of your installed charts as described under "A few hints" below. Look for the rectangular outlines of the installed charts. An alternative is to right-click, and then click "Jump to position". Enter a location that is within the perimeters of your entered charts. The first time you start OpenCPN the view will be centered on Georgetown in South Carolina.

Quilting Chart Mode is the default display mode. In this mode all available charts at the viewpoint will be quilted together seamlessly according to certain roles. Read more in Chart Quilting. The other display mode is Single chart Mode were only one chart at a time is used. It is possible to read all the information printed in the perimeter of a raster chart. To change to another chart, select and click in the Chart Selection Bar. Read more in Status Bar.

Starting with vector charts?

If you are new to vector charts, including CM93 v2, on OpenCPN follow this quick-start guide:

1 Go to Options ->Charts-> Vector Chart Display and copy the settings below for the Display Category.

2 Press this button in the ToolBar to toggle text display. Alternatively, the "T" hotkey does the same thing.

These are not the "perfect" settings, but you will see most of what you expect from a vector chart.
As soon as you have made yourself reasonably comfortable with OpenCPN and before using Vector Charts for actual navigation, make sure you understand all the settings in the Options-> Charts -> Vector Chart Display Tab by reading the Vector Charts page.
Loading Vector Charts
When using a vector chart for the first time, OpenCPN has to process the data, and transform the information to an internal display format. Click the green chart rectangle in the chart-bar to start the process.

This can take some time, depending on your computer. This internal SENC chart, is saved for future use. The created files are quite large, but is in a format optimized for quick loading. OpenCPN is trading, creation time and size, for fast rendering when actually using the vector chart. The SENC files are saved in the SENC directory, in the same place as the opencpn.conf file - opencpn.ini on windows.
To avoid getting a very long series of SENC charts being built at the same time, use single chart mode, for better control. This is certainly called for in areas that are densely populated with vector charts. Single chart mode and quilting are explained on this page Chart Quilting .
You probably do not want to build SENCs for all of your loaded S57 ENCs unless you plan to actually go there....
For an advanced approach to building all SENC files in one go .. The Command Line
Updating Vector Charts
Publishers of Vector Charts, such as NOAA and EAHC issues regular updates. OpenCPN updates the created SENCs automatically. The chart itself, the base-chart, is named "name".000 , the first update is "name".001 and so on. As a user you only have to make sure that the update files are saved in the same place as the base-chart. In the case of a new edition of the chart a new "name".000 file is issued. Just replace the old file with the new file and OpenCPN will update the SENC file. Don't forget to remove the updates to the old edition of the chart.

In case of missing revisions in a series of updates errors may be introduced. OpenCPN will pop up a warning dialog with this content:

"S57 Cell Update chain incomplete. ENC features may be incomplete or inaccurate. Check the logfile for details."

CM93 Charts
CM93-version2 Charts are different from the S57 vector charts, and has it's own data structure consisting of a number of folders and files. To load these charts in OpenCPN just add the top directory to the list of "Active Chart Directories".
In the top CM93 directory is an empty file with the ".EXD", for example 20110803.EXD. The format is YYYYMMDD.EXD. This is the version, or edition, of the CM93 -v2 release.
OpenCPN supports partial CM93 datasets, covering one or a few of the available regions. There is also support for multiple, as well as multiple partial, CM93 datasets.
The CM93 top directory contains a number of (144) subdirectories named from
"00300000" to "04501020", as well as six other files. These sub directories each cover a geographical area of 40° x 40° . The first four numbers describes the latitude and the last four, the longitude of the SW corner of the area covered.


This is a typical content of the CM93 V2 top directory.

The key to understanding the numbers is to realize that CM93's coordinate system
of the world starts at the South Pole or to be exact at lat -90° long 0° and from there
proceeds North a East with a factor of 3 for each degree of lat and long.
The tile 00300000 hence has the SW corner at lat from -90° + 0030:3 = -80° or 80°S to
and longitude 0°E , and covers the area from 80°S latitude to 40°S and from 0° longitude to 40°E.
Looking at 04501020 it brakes down to lat -90° + 0450:3 = 60° and long 1020:3 = 340° subtracting 360° results in -20° or 20°W. So we have he SW corner at 60°N and 20°W .
One more example, the tle 03900840 has the SW corner at 40°N and 80°W.

Each of these sub-directories in turn contains directories with the individual charts. Ordered in scale from smallest to largest they are Z,A,B,C,D,E,F and G. Where Z contains overview charts and G contains harbor plans. Note that, generally, not all of these are present in each subdirectory.

Z covers 40° x 40° deg area and OpenCPN typically uses 1:3.000.000 scale
A covers 20° x 20° deg area and OpenCPN typically uses 1:1.000.000 scale
B covers 10° x 10° deg area and OpenCPN typically uses 1:200.000 scale
down to
..
G covers 20' x 20' and OpenCPN typically uses 1:3500 scale.
The individual chart tiles in these directories have the same logic in the naming scheme as described above.

A few hints.

• If you ticked the "Show Chart Outlines" box under the "Display" tab the loaded charts will be outlined in red for raster and green for vector charts. In CM93 the charts will be outlined in purple, but only in Single Chart Mode. The smallest scale charts in CM93, the Z scale and A scale charts, will not be outlined. Neither will all available charts be visible as outlines at the same time. The reason for this is computing speed and clarity. Generally the next level or two of larger scale charts are shown. When large scale plans are available directly from A scale charts, with no intermediate charts, the outline of the larger scale charts will be visible from a zoom level between 1.5 and 2.0, but only, as already mentioned, in single chart mode and with chart outlines switched on. Generally in areas where only A or Z scale charts are available, expect potentially dangerous omissions.

Warning, do not use CM93 small scale charts alone for navigation without referring to other sources.

• Be aware that it is possible to "Over-zoom" charts in OpenCPN. A warning will appear on the display. Please respect that warning. It is recommended to not zoom more than a factor 2, for safe navigation. The actual zoom-factor appears in the lower right-hand corner of the display.
• It is safe and reasonably efficient, to put all your charts except the CM93 database in one large directory, and set that directory in Options->Charts->Chart Files. The CM93 database contains its own file and directory structure. The top-level directory only, of this database, should be loaded, as described above.
  If you do a lot of chart downloads, updates, etc., then it will be faster to break the charts folder into smaller groups, and specify them individually in the Options->Charts->Chart Files dialog. Consider using Chart Groups
• "Scan Charts and Update Database " Use this option if you have made any changes to the contents of your chart directories, as for example after downloading new charts from NOAA, etc. It need not be checked if directories are added or subtracted, as the entire database will be scanned and updated automatically in this case.
• "Force Full Database Rebuild" is mainly aimed at users converting or correcting existing charts, in a situation where changes are made to the geo-referencing, outline of the chart, or other attributes in the kap file header section.
• OpenCPN, supports Mercator Charts, Transverse Mercator Charts, Universal Transverse Mercator (UTM) Charts and Polyconical Charts (used in parts of US and Canada). Charts using other projections will not be displayed. A note about the reason for the display refusal, will be found in the "opencpn.log".
  "Other" projections could be Lamberts Conformal Conic Projection, mainly used in high latitude polar areas. Gnomonic charts, mainly used in older, larger scale BA charts, for smaller areas, for example harbor plans, in scales larger than 1:50,000. Newer editions of these charts are generally re-issued as Transverse Mercator charts. Gnomonic projection charts are also traditionally used for Great Circle Sailings. Such charts are not needed in OpenCPN, as Great-circles are handled internally.
  
• OpenCPN is not suited for Polar Navigation N/S of about 70 degrees. As long as there are Mercator charts available, OpenCPN is OK though. There are some charts available up to 80 N, for example Norwegian chart for the Northern part of Svalbard. The Mercator projection is not generally suited for polar areas, with quickly converging meridians. Small scale (less than 1:100,000 ) high latitude Transverse Mercator Charts, with clearly converging meridians, cannot be displayed correctly. Other projections suited for polar areas can't be displayed at all in OpenCPN.

A Linux/Unix Note
These operating systems have a problem handling chart names containing spaces and non ASCII characters. A typical example is Swedish chart names.
To sort this out use the utility program "detox". Detox changes the file names so space becomes "_"; "(" and ")" become "-"; and "å","ä" and "ö" become "a","a" and "o", etc. To see what "detox" suggests to do, try a dry run first, like this:
detox -n File_with_swedish_charts > outfile

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Chart Info

If you hover the cursor above one of the segments, representing a chart, in the Chart
Selection Bar, a chart information box pops up. The chart info refers to the chart in the upper right corner, outlined in red and with pink-ish overlay.


The information on a vector chart is similar.



For CM93, switch to single chart mode, to see the information.
If there seems to be a lot of information missing, it's because the chart has not been viewed in the present session. Get the chart up on the screen, the try again.
The Chart Info Box can be inactivated by hiding the Chart Bar. Use Hot keys
Ctrl + B to hide/show the Chart Bar.

What does all the information mean?

ChartFile: The file on the local computer where the chart is.

Name: The Name of the Chart. Not all vector charts have names, while raster charts always have names.

Scale: The scale of the chart.

ID: The chart number. For raster charts this is the same as the number of the paper chart. Vector chart cells have their own numbering scheme.

Depth Units: For raster charts this is the units for the printed soundings. For vector charts this is the sounding units set in Options -> Display -> Units -> Depth.

Soundings: The datum for soundings. It is the level that all printed depth figures refers to. Consult a text book on Navigation for details.

Datum: The geodetic datum. This will be WGS 84 for all new charts, compiled later than about 1993.
If this value is missing, unknown to OpenCPN, or stated as "UNKNOWN" or similar, OpenCPN will not load the chart. The fact will be logged in the logfile.
See below for an example of this kind of chart.

If the chart is not using WGS 84, but a named, recognized datum, OpenCPN will automatically add necessary corrections.

Projection: OpenCPN accepts Mercator, Transverse Mercator, UTM or Polyconical projections.

Source Edition: The Chart Edition.

Updated: The date when the chart was released. Expect the chart to be updated to this date, unless otherwise stated.

The OpenCPN Logfile

The file contains a wealth of information, and should be your first stop if your chart(s) don't load or if there is an error message.

Chart Accuracy

First... make sure your GPS is set to output positions using the WGS 84 Geodetic Datum.

If you see a warning like the one below:


Be careful. The warning means that the charts geographic accuracy is bad. The position of Own Ship may not be correct.
A visual warning is that Own Ship turns from Red to Yellow when receiving a gps signal.

First is a real scale vector version and then. the default OwnShip bitmap


There is no quick fix for a bad chart, but try to switch to another chart if using single mode chart display. If quilting is on, right-click on the chart button in the chart-bar and select "Hide this chart". Both suggestions assumes that the bad chart can be replaced by other charts, which of course isn't always possible.
The chart will probably be OK for navigation with traditional methods. Use bearings, vertical or horizontal sextant angles of conspicuous landmarks to confirm your position, as well as soundings or any other available resources.

Checking a chart for accuracy

A raster chart, using a named, recognized, Geodetic Datum, for example WGS 84, can be checked for the accuracy of the chart grid. This does not necessarily guarantee the position of the individual features on the chart. Refer to Calders book.
Activate Options -> Display ->General -> Show Grid. A Latitude and Longitude grid will be displayed as a layer on top of the chart. This grid is OpenCPNs view of how a proper WGS 84 should look like. For raster charts this grid can be compared to the "printed" grid on the chart picture. Chart errors are to complicated to be treated in a few sentences. Refer to Nigel Calders book "How to Read a Nautical Chart" for an in depth but still easy to read text.
For a quick check, we are happy with a grid error that is in the region of 1 mm at the chart scale. For a chart in 1:50.000 this means an error of 50 m.

Use OpenCPNs ability to grossly over-zoom a chart. Home in on a printed lat/long crossing. Below is a test on a commercial BSB3 chart in 1:60.000. The width of the printed grid - thick black lines - is about 12 m. The thin gray lines is OpenCPNs grid layer. The accuracy of this chart is very good.





Another example. This time we are looking at a chart in 1:10.000. Very accurate.

No Projection -> Chart rejected.

If the chart does not contain any information about the projection, OpenCPN don't know how to display them. From Version 4.0, such a char will not be loaded, but a note about the problem will appear in the log file.
Missing a chart? Check your OpenCPN logfile.

No Datum -> ---<<< Warning: Chart Datum may be incorrect. >>>---

The message will be in the Chart Info Box.
This is a warning that the chart probably is not accurate enough for GPS navigation. It still should be OK with traditional methods. A minimum recommendation is to check the GPS position with traditional methods, a couple of compass bearings, for example.

One example, that unfortunately have lead to problems for a few yachts, is DMA/NGA chart 28201, Puerto Morelos, in Mexico, from 1995. This chart, based on a Mexican survey from 1905, has a Datum Note, similar to this:




Comparing 28201 with CM93 that is correct, in this particular case. Note the substantial corrections applied in CM93,

Chart Quilting

Chart quilting is a way to display parts of several charts together on the screen, redrawn to the same scale.

Limitation
Mercator charts, Transverse Mercator charts and Polyconic chart are quilted separately and don't mix. The transition from one form of quilting to the other is seamless. The background world chart can appear in Tmerc and Polyconic quilt in areas where there is no other chart coverage.
By quilting, any information available in the white border around a chart, will be hidden.
To see this information hit "Q" to get into single mode display.
Skewed charts don't quilt, unless the skew is less than 5°.

Quick Start
Go to Options -> Display ->General -> Enable Chart Quilting. Tick he box. Another, simoler way is to use the "Q" short key to toggle quilting on/off. Zooming in, automatically brings up larger scale charts, if available. Panning reveals a continuous quilt of the available charts. If you started with a raster chart, only raster-charts, and perhaps CM93, will be in the quilt. The same logic applies to S57 and S63 Vector Charts (ENCS). Make sure you are familiar with the Status Bar as this will help you interpret all available information. The quilt, like a single chart can be displayed North Up or Course Up read more: Auto Follow and Display Orientation.

More details
What is the use of this feature?



In single chart mode, getting near the edge of the chart there is no information outside the chart. You manually have to change to the next chart, by selecting one of the charts in the chart bar.

The situation changes dramatically when quilting mode is activated. The amount of relevant information on the screen increases, and the next chart is automatically available.

Displaying charts

OpenCPN has two modes of displaying charts, single chart mode and quilting mode. Quilting is the default, and is on in a new installation.

Single Chart Mode only shows one chart at a time, and a switch to other charts must be done by clicking another chart in the Chart Bar. All printed general chart information, outside the chart proper, can easily be read.

To activate chart quilting go to Options -> Display->General and tick the box "Enable Chart Quilting", or use the shortkey "Q" to toggle quilting. Tick the box "Show Chart Outlines" at the same time as this will help you see which chart mode is active. For CM93 the outline of individual charts can bee seen only if quilting is disabled.

Full Screen Quilting. Options -> Display -> "Disable Fullscreen Quilting". By default all visible charts of an appropriate scale are used in the quilt. With this box checked only charts that overlap the center of the screen are used in the quilt. Checking this box is easier on the system and may give a performance boost in certain circumstances.

Is Chart quilting on?
There are some visual indications on screen to confirm if quilting is on or off.

• If the right click menu contains the entry "Hide This Chart", quilting is on. Clicking the entry excludes the chart from the quilt.
• The colored rectangles in the status bar have rounded corners and the white borders of the charts are invisible when quilting is on. When quilting is off in ToolBox->Settings, the colored rectangles have "square" corners.
• If you have the status bar visible at he bottom of the screen, a value in brackets after the scale, to the far right, is only shown in single mode. The value within the brackets is the zoom factor.
• When hovering with the mouse pointer over a inactive raster chart button in single chart mode, a thumbnail of the chart is displayed in the upper left corner of the screen. At the same time an information box pops up above the button with details about the chart. This changes with quilting, as the thumbnails are replaced with a transparent reddish high-lighting of the charts that is a part of the present quilt or has a larger scale than the reference chart in the quilt. This means that if Mercator charts are quilted the Transverse Mercator Charts will not be highlighted, and vice versa.
• The exception to the last rule is CM93 charts. When an area is only covered by CM93 charts, indicated by a long yellow chart button in the status bar, and in quilting mode, no info-box is displayed and no reddish highlighting is taking place.
• When CM93 quilting is off, the outline of the individual cells are outlined in magenta.

More than one chart can be displayed and active at the same time, on the picture above, for example there are two pale blue buttons, as there are two raster-charts in this quilt. In single mode only one chart button is highlighted at a time.

Depth units that is normally shown in the upper right corner of the display, if activated in the toolbox, is only displayed in quilting mode if all participating charts uses the same unit.
Zoom level, normally displayed on the far right on the Status bar, is not present in quilting.

Many of these features are illustrated in this screen-dump.



This is a quilt consisting of three raster charts, two that are actually displayed and one smaller scale chart that is hidden behind the larger scaled charts of St Croix.
This is the button for the not displayed chart in the quilt.
The mouse pointer is over the middle raster chart and the chart information box is shown, together with the red highlighting of the chart on the screen.
If the chart info box contains much less info than above, just click the button to display the chart, then go back and hover with the cursor over the chart button again. The full info will now be available.
No depth unit is shown in the quilt as the left chart is in Feet and the right in Fathoms and parts thereof. Notice the lack of zoom level in the status bar, a quilt , by definition, consists of several different zoom levels.

Which charts are quilted?
There are several rules built into OpenCPN governing exactly how different charts reacts to the quilting mode.
Raster charts and Vector charts are quilted separately and don't mix together. You can quilt either raster charts or vector charts, but not both at the same time.

The exception to this rule is that CM93 ver2 charts, if available, are shown if no other Mercator chart cover exists for a displayed area, for both raster- and vector- chart quilting.

CM93 chart also kicks in (if available), if the view is so far zoomed out
that the rightmost (smallest scale) raster chart is too small to be useful. OpenCPN remembers that this selection of CM93 is due to attempted under-zoom of a raster chart. Then, when you zoom in again, it tries to return to the raster chart that caused the auto-shift to cm93. If that chart is not available, it makes best effort to find a useful small scale raster chart.

Transverse Mercator Charts, which are all raster charts, are strictly quilted on their own. In this case, the background map is visible where there is no coverage.
Polyconic Charts, which are all raster charts as well, are also quilted strictly on their own. The background world map is visible where ther is no other chart coverage.

CM93 ver2 charts can be quilted separately.

Mercator Charts are always quilted in quilting mode but don't quilt together with Transverse Mercator charts or Polyconic charts.
Polyconic Charts, are quilted separately, and don't mix with Mercator or Transverse Mercator Charts
Skewed Charts are allowed in the quilt as long as they don't deviate more than 5 degrees
from North Up.
Transverse Mercator Charts are quilted separately from Mercator- and Polyconic- Charts.
"BSB4" and "nv-charts", using plugins, quilts with other Raster Charts, following the rules above.

User control.
Users can control if an individual chart, is allowed in the quilt or not. Right clicking on any chart in a quilt in the chart-bar and clicking "Hide This Chart" on the pop up menu, removes the chart from the quilt. The chart button in the Status bar changes to . The same thing can be achieved through the right-click menu when clicking on a displayed chart.
To activate the chart again right click this button an then click "Ad this chart to quilt"

Controlling the scale of the quilt view.

The "quilt reference chart" is the left-most, largest scale chart, highlighted in the chart bar. This is the left of the two pale blue chart buttons above.
Click the next chart blue button "one-to-the-right" of the of the current reference chart. The reference scale of the quilt will be decreased, but the viewpoint will not change. The same logic applies if clicking a chart-to-the-left of the present reference chart, except that the scale of the quilt will increase. Zooming in/out will also move the reference chart to the left/right.

Known issue with some NOAA ENC:s



Some NOAA ENC:s are produced with "holes" in. OpenCPNs handles almost all of these cases. The picture above is from S:t Croix in the Caribbean, using an old version of OpenCPN. There are still some gray areas in this vicinity but only if the scale is larger than 1:10,000. Very few users are likely to notice this.
The gray rectangle above is a "hole" in a chart, where a smaller scale chart with coverage exists. The "hole" is due to the fact that this area wasn't surveyed to the scale of the chart.



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Chart Groups

Chart Groups solves the following problem: You may have many charts loaded in your active database. Some of them have overlapping coverage at the same scale, so that when quilted the logic does not know which of potentially several charts at the same scale to choose from. For example, in the Bahamas there are a few publishers of charts, covering the same areas, with radically different presentations. Sometimes you may want to see one set (say planning charts of small scale), and other times you only want navigation charts of the best scale possible.
Another example: Pilot charts as one Group, normal navigation charts as another Group, makes it possible to quickly switch between them.

Final example: in another universe, NGA charts in one group, standard NOAA RNCs in another, British UKHO in a third group.

The Chart Group function allows us to define multiple Groups, with different chart directories in each group. It is possible to leave a Group empty, in which case only the background chart will be displayed. The Group desired for viewing may be selected quickly, through the right-click menu, without adding or deleting charts from the Active database.




In Options ->Charts, select "Chart Groups"
You will see two panes. The top pane contains "All Available Charts", which are the charts you have installed. The bottom pane allows you to create, edit, and delete Groups. Note that there is always an "All Charts" group. This Group is not editable. New Groups which you create may have chart directories or individual charts added to them by selecting the item in the top pane and touching the "Add" button.
You may also remove individual charts or directories from Groups by selecting the desired item in the bottom pane, and touch "Remove Chart". Please note that "removing" an item from the Group does not remove it from your "Available" set of charts. The item is simply made unavailable when the Group is in use.
It is a good idea to have a empty chart group, only the background Map will be shown. "Unlimited" zooming is allowed. This can be usefull for very lage scale plotting, for example.

Using your Groups

In this illustration the navigator generally uses the US charts, when available. Coming into Baia do Porto Santo a detailed chart would be great, but no such US chart is available on board. A switch to the UK chart group solves the problem.





Select the Group you want to use, by a right-click context menu item called "Chart Groups". As you switch Groups the logic tries to select a chart and scale that closely matches the situation present before the switch. As you may understand, sometimes the fit is not reasonable, so the resulting view may be surprising.

Finally, if you have no Groups defined, as in the default installation, all installed charts are always available.

Chart Groups and CM93



It is possible to have multiple instances of CM93v2 in different Chart Groups. Above we have 5 instances loaded in various chart groups. The view is of "All Active Charts".
OpenCP also supports multiple partial CM93 data sets.
The instances are loaded, from left to right, in the order of the chart groups.
In this situation, only the leftmost instance of CM93, that is not excluded from the quilt, will be displayed. Above, it is the instance represented by the yellow rectangle.

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Vector Charts

OpenCPN makes a serious effort to be compliant with IHO standards for ECDIS display of cartography.

First, one very important setting for vector charts is handled directly from the main toolbar.
This button toggles all text displayed on a vector chart On and Off.
The hotKey "T" is an alternative for toggling the text.
In OpenGL mode, all text will always be horizontal when using the "Course Up" option.

Second, double clicking on a vector chart, as long as the cursor hasn't changed to a green arrow near the edges, brings up an information dialog, displaying the available vector-chart information at the selected point. Scroll down to see all the information. An alternative to double clicking is right-clicking an select "Object Query".
Note that a single normal (left) click will center the chart at that point.



The example is taken from double-clicking on a lighthouse in a busy area.
Exactly what is shown in this dialog depend on the settings described below in "Display Categories".

Third, it is possible to select what font is used for the text on vector charts. There is an entry in theToolBox->Languages/Fonts->Choose Fonts tab, called ChartTexts. Here you select what font-face to use, and a template size. Weight and final size of the displayed texts depends on the charts you are using, but if the charts contain various weights and sizes, they will all scale together depending on what size you select.

The Options-Charts-Vector Charts Tab is where everything else is handled.
If the S63 chart plugin is active, there will also be a "S63 Charts" tab. Read more about S63 Vector Charts,when you have read this page.

Display Categories

If you are new to OpenCPN and vector charts please start with the "All" Display Category, to avoid risks and possible confusion. More below.

Navigators has the choice of three pre-defined, different, presentations of ENC content, Base, Standard and All. OpenCPN also has the very flexible Mariners Standard, which is better described as "Mariners Choice".

Base

Displays general information, including coastline, safety-contour, isolated danger,
buoy, beacon traffic separation zone, etc.

From the IMO definitions:
Display Base means the level of SENC information which cannot be removed from
the display, consisting of information which is required at all times in all geographic areas and all circumstances. It is not intended to be sufficient for safe navigation.

Standard

Everything in "Base" and aids to navigation, fairways, channel limits, restricted navigation zones, restricted areas, etc..

All

Everything in "Standard" and more. This level shows all informatio, not contolled in other settings options. More about what the IMO ECDIS says about the content of these three levels. This is also a good choice for actual, underway, navigation, avoiding the possible risks involved in "Mariners Standard". See more below.

Mariners Standard

Users can use the filter tick box to set exactly what he or she wants displayed. A large set of filters, about 186, can be employed. They are all to the IHO S57 standard, but has been given a label that is easy to understand.
Note that Mariners Standard gives the user a much wider choice of what to display, than approved ECDIS system are allowed. It is for example possible to not display items in the Base category.

These Hot Keys all works in "Mariners standard". Features are toggled on/off with the keys.

T	Texts. The visible texts are still affected by the settings in the Vector Charts settings tab.
L	Lights. Lighthouses as well as buoys etc are all affected.
S	Soundings.
A	Anchoring. This will affect information needed when anchoring. Anchorages and anchorage areas. Submarine cables and pipelines. Type of bottom.
O	Chart Outlines

WARNING - it is possible to suppress essential information with "Mariners Standard".

If in doubt, switch to the "All" Display Category, or use the "Select All" button for Mariners Standard.

More Details.

The first time you use a vectorchart with a brand new installation you will see nothing, if you use Mariners standard. Why? The Mariners Standard list of Feature types is empty on a fresh install. When you load the first vector chart, the list is populated with the Features that are discovered on that particular vector chart. The default visibility of the added Features in MarinersStandard category is presently 0, invisible.(This will soon change. Version 3.4, when released, will show all features as they are discovered.). If you load another ENC, any newly discovered Feature types are added to the list, again with viz=0, off. However, the visibility of Feature types as set previously by the tick boxes is not modified. Use the "Select All" button frequently untill you have initiated all the charts you intend to use and/or the feature list is fully populated

Vector Palette

It's possible to change the whole look of a vectorchart. One example below....
Detailed information is available in Vector Palette

Practical usage

A general recommendation would be to use the "All" display category or "Mariners Standard" with "Select All" marked , and then switch of certain features as required.

As an example let's look at passing through the British gas fields in the SW North Sea



This is not easy, so we want to get rid of all those red and yellow circles.
Doubble click on one of the platforms, square with a dot.



At the top it reads "Light (Lights)", which means that you clicked on a light, whis belongs to the Feature Class "Lights".
Find "Light" in the Mariners Standard list of available filters, and untick it.



Press the "Apply" button!



Much better!
In this particular case, there is a shortcut which does the same thing. Use the Hot Key "L" to toggle all lights on/off.

Display

Depth Soundings turns the depths on and of. Other settings also affects when soundings are displayed, for example "Reduced Detail at Small Scale". The dark black numbers are not soundings. Instead they refer to heights of nearby islets or cays. On official paper charts the soundings are printed in italics.

The bold number 20 refers to the land height of the unnamed cay SW of the number.
"Safety Depth" is set to 20 m, so the 20 m contour stands out in black.

How soundings behave when zooming.
"Chart sounding symbols" are represented by small raster images. As a chart is zoomed in, these raster symbols will increase in size by about 2x. Currently they increase in size well after the "Overzoom" notice, for the largest scale chart available.

Chart Information Objects relates to information about the chart itself. With this switch on, an object query reveals such information as the buoyage system for the area, the quality of the survey, the latest NTM update and sources for the chart.

Buoys/Lights

Bouy/Light Labels, displays names and purposes of aids to navigation, such as number or name of buoys, information about conspicuous objects etc.

Light Descriptions, this tick box control display of light characteristics. Checking this displays a label with a text describing the marker or lighthouse's characteristics.

Extended Light Sectors. It is often difficult, on a vector chart, to see exactly what the light-sectors are supposed to do.

Activating the Extended Light sectors clarifies the situation. All sectors are extended and leading white sectors are emphasized in yellow and extend the full nominal range of the light. Just hold the cursor over a ligt and the extended sectors are activated.


Light sectors as narrow as 0.3° are displayed.


This sector is 0.5°.

More Details.

A light sector is extended if: 0. The words "Leading" or "Directional" can be found in the Object Query. Otherwise, the rules are 1. The sector is < 15° wide. 2. It is White. 3. The light also has Red and/or Green sectors. These rules works quite well, but there are exceptions that are difficult to catch. As always, it's the responsibility of the navigator, how a light and its sectors are used for practical navigation.

Chart Texts

National text on chart. Vector charts may have attributes with the texts in the national language. For example a Russian chart with texts in Cyrillic. With this option activated OpenCPN will display text in the local language and character set, in this case Russian written in Cyrillic.

Important Text Only displays only a bare minimum of text essential for navigation, such as course and bearing in a leading line (range) and bridge clearances.

De-Cluttered Text. Even when using "Reduced Detail at Small Scale", there are cases when text labels overlaps or overwrites other labels and creates a cluttered impression. Ticking this box tries to clear the view. This setting may hide needed information.

Chart Detail

Reduced Detail at Small Scale makes sure that a minimum scale is required before certain objects are shown. If this box is not ticked, everything is always shown, leading to very cluttered view at small scale (zoomed out).

Graphics Style

Paper chart draw the markers and lights just like the printed paper chart, while Simplified uses icons to represent the same. Some like the one and some the other, a matter of taste.
Paper Chart mode closely follows the IHO standard standard in this area. This mode is currently more developed than the simplified mode, as it has a higher priority in the development effort.

Boundaries

Plain normally just uses a dashed line, while the Symbolized version also uses triangles pointing into the area.

Colors

Depth on the chart can be displayed with either 2 or 4 colors. This setting is closely related to the "Depths Settings". With 2 colors, and using a relatively large scale, areas with depth less than "Safety Depth" is blue, the rest is white. With 4 colors, there are different colors for areas less than "Shallow Depth", areas between "Shallow Depth" and "Safety Depth", areas between "Safety Depth" and "Deep Depth" and finally for areas deeper than "Deep Depth".

Depths Settings

The units for depths is set in Options->Display->Units.

All depths units are rounded off to the nearest number. If the value is half way between, the nearest higher number is used. Underlined values indicates drying heights.
Feet
Only whole digits are shown. A value of 12 feet covers all soundings between 11.5 feet and 12.4 feet.

Meters

Meters are show as whole numbers for depths greater than 30 m. Depths below 30 m are shown as whole meters and decimeters as subscript, like this 12₇ This is the same as 12.7 meters and is shown for all soundings between 12.65 m and 12.74 m.

Fathoms

Fathoms are show as whole numbers for depths greater than 31 fathoms. Depths below this value are shown as whole fathoms and tenths of fathoms as subscript. Compare to the notes above for meters.

_{Shallow, Safety and Deep depths}.

<sub>These settings are very important as they affect how the different depths are colored.
They can help you identify a deep channel for example, or they can, in the worst case scenario, prevent you from being aware of a shallow area.
There is no setting that fits all circumstances. For example a Sea Mount with a depth of 20m in the middle of an ocean should be regarded as "shallow" and be avoided, while 20 m depth in a harbor approach in protected water, probably is safe.

The Depth Settings controls the coloring of the water as a function of depth. By setting the Safety and Deep water right you will have a visible border to show when to take care about shallow water.
CM93 charts and ENCS works very similar in this area. The charts contains depth area features according to fixed depth cutoff zones, usually 5, 10, and 20 meters. Intermediate values are not available in the database,if you select a value between those available, OpenCPN chooses the next higher value available for display of color.
The charts are inconsistent in this area, depending on the country issuing the original charts. For example in UK and the Netherlands the depth contours in CM93 are 2, 5 and 10 meter while in US the are based on feet but expressed in meters, such as 3.7, 5.5, 9.1 and 18.3 m.
Generally for both ENC and CM93, find these fixed depth cutoffs by double-clicking so the Object Query dialog pops up. The last entry is usually Depth Area. The two values in the range, represents these built in cutoffs.


An example from UK with cutoff values of 5m and 10m.

If for example, as is the case on the South China Sea Hydrographic Commissions charts, the shallowest area has a range "0 m - 10 m", there is, in most cases, no point in setting "Shallow Depth" to anything but 10 m.
Find out these cut off depth for your area and set the "Depth Settings" with this knowledge together with your preferences and activity.

With all the reservations above, the general case for 4 colors, will be described.</sub>

_{Shallow Depth}

_{will color all water areas with water depths shallower than the set depth to a dark blue color. Soundings are in black.}

_{Safety Depth}

_{Water deeper that Shallow but shallower that this depth will have a paler blue color. The Shallow Depth contour clearly marked with a thicker black borderline. Soundings less than this depth are in black, while soundings greater than this value are gray.}

_{Deep Depth}

<sub>Water deeper than Safety Depth but less than Deep Depth will display a light gray color. The Safety Depth contour is clearly marked with black borderline. Water deeper than Deep Depth is displayed in white.

Finally a word about drying heights, displayed in green. There is no detailed information available for drying heights, neither in CM93 ver2 nor in many ENC charts. Some ENC charts have negative ranges, for example "-2 m - 0 m" in areas with drying heights. This adds very little, as it really only gives the information that the drying height is less than the first value in the range, in an area of unspecified size.
This situation is changing though. A set of new charts released in april 2012, by the Dutch Authorities, sets a standard for others to follow in this regard. See picture below. Modern Australian S63 charts are equally good.



Compared to CM93.



When is safe to pass across Bramble Bank? The CM93 vectorchart gives you no information whatsoever, neither on the chart, nor in the Object Query dialog.



While a raster chart tells us that we need a Hight of Tide that is 1.2m + safety margin + the draft of our own vessel.



Heights of islands etc. are not available in CM93, while ENC charts, in many cases, have info about heights of summits and some contour lines.
Is Balls Pyramid a high Island, that the name implies, or is it named with the same sarcastic humor as "Greenland" ? CM93 can't tell.</sub>

CM93 Detail Level (d)

The CM93 charts slider control that allows the user to adjust the screen complexity to suit the actual situation as well as the available processor capability.
Normal settings depend on a combination of personal preferences and present usage of map. To see more details, the "CM93 Detail Level" slider, can be set to a higher positive number or for navigation in shipping lanes to a negative numbers. Typical zoom level 5 is good for fishing when as much details are possible is of interest. Zoom level of +1, zero or -1 is usually fine for normal use.
Positive values give more detail, but at a cost:
a. It simply takes longer to render larger scale charts covering more screen real estate.
b. There will be more instances of gray (NODATA) areas surrounding the larger scale charts as you zoom out, unless quilting is activated.
c. It can become dramatically slower if high detail is specified, and chart outlines are requested. In this case, the program has to read a lot more cells to get their outlines.

Conversely, negative values give less detail. Zooms are faster.

The slider can also be activated through the "d" hotkey, and displayed directly on the screen.

_{Go to Table Of Contents}

Vector Palette

JesperWe's Swedish look palette.
The default style can be changed to look different! You can download files that give the charts a Swedish look (new colors, soundings and underwater rocks). Unzip and move the two files into the s57data folder of your installation and you get this:


* Download "Swedish Style"

We are looking for more "styles". There is a French style... somewhere.
Can someone supply a change file similar to Jespers ?

S63 Vector Charts

Chart showing Part of Jamaica, from the IHO S63 test suit.

S63 is an encrypted version of S57 vector charts, and is the standard format for almost all, officially published, vector charts in today’s world. As a matter of fact, only NOAA and the East Asia Hydrographic Commission (EAHC), publishes free unencrypted S57 charts nowadays.

These, S57 and S63 charts, are the current state of the art charts. The quality of the charts are the best vector charts available. They are always kept up to date. No other vector chart are in the same league.
There are, however also some drawbacks. Many popular cruising areas are very poorly covered as the focus is on the needs for commercial shipping. One example is he Bahamas area. Another problem is the relatively high price.

OpenCPN handles these commercial, non free, charts through an open source plugin, that in the background connects to a "black box" helper application. An external entity, o-charts.org, handles the encrypted and commercial aspects of the S-63 plug-ins for OpenCPN.

Get Started

• Download the plugin for your operating system from http://o-charts.org/downloads.html. On the same page download your fingerprint executable, that will be needed later. Also download and read the informative Documentation.
• Install the plugin the way you normally install programs on your operating system.
• Go to Options->Charts-Plugins. Find the S63 plugin and click "Enable" and then "Apply" or "OK". The "Preferences" button is grayed out, as there are nothing to set.
• Check thar your Options->Charts has a new "S 63 Charts" tab, as in the pictures below.
• Now go to the O-charts shop to get your "User Permit" and "Install Permit". Use these to buy your chart selection.
• Detailed instructions are available on o-charts.org

Loading the Charts

The Keys/Permits tab.

• Certificate Name This should already be present after a sucessfull plugin installation.
• If it's missing press the "Import Certificate..." button and import the file IHO.PUB. To find the location of this, file press the button in the toolbar. Find the " Config file location" at the bottom of the "About" tab. Go to the same directory as the config file, and then s63->s63_certificates directory, where you will find IHO.PUB.
• UserPermit

• Enter your new Userpermit from O-charts and test it. The permit above is from IHO's test suit and is not valid in real life.
• New InstallPermit

• Enter your new Installpermit from O-charts and test it.
• OpenCPN is now setup for S63 charts. Buy your charts or use the test set. See instructions below.
• Download and uncompress your files.
• Install Cell Permits by using the button "Import Cell Permits..." to find the file PERMIT.TXT.
• Import the downloaded charts by pressing "Import Charts/Updates.." and find the folder "ENC_ROOT"

• This dialog will pop up. I you answer "No", the SENC creation will happen when you first try to use the chart.

Testing

Download http://www.iho.int/iho_pubs/standard/S-64/ENC_Test_Data_Sets/ENC_TDS_S-63_Encrypted/ENC3.1.1_TDS_S-63_Encrypted.zip

You may exercise the S64 Test set using the following special permits:
User Permit: 66B5CBFDF7E4139D5B6086C23130
Install Permit: 38F99B50

Perhaps the best to start with is:
IHO S-64 [S-63 TDS v1.2]/8 Data Exchange Media/Test 8b/PERMIT.TXT

Chart Sources

High Resolution Background Map

A more detailed version of the built in background map is available here.
It is a big file, 230 mb(unzipped) compared to the standard 26mb, and may slow your computer down. The presentation is better when zoomed in, but most users don't need it.
Install by unzipping and placing the files in the <install_dir>/gshhs .
<install_dir> is normally ...Program Files/OpenCPN on Windows and /usr/share/opencpn/ on a Linux default installation.

Free Nautical Charts

• To get you started quickly, here are three sample raster charts from Puerto Rico:
  • 25640, Puerto Rico and Virgin Islands,
  • 25664, Fredriksted Road, and
  • 25666, Ensenada Honda.
• Right click and use "Save Link As", or similar. Just clicking shows you the actual file as a text file (more about that advanced subject here:imgkap). Don't use these charts for navigation. Download their current versions from NOAA's Web site. Save the charts in a "directory", also called a "folder". Install the charts by adding this directory to the Options -> Charts -> "Loaded Charts" Tab.
• For those interested in U.S. waters, raster charts and S57 vector charts are available as free downloads from NOAA. Find all NOAA charts, both raster (RNC) and vector (ENC) charts, for your region through NOAA OCS Website at: http://www.nauticalcharts.noaa.gov/staff/chartspubs.html. US charts cover a wide area, apart from the mainland states, Puerto Rico, the US Virgin Island, the Hawaiian Island chain as far as Midway Island, American Samoa, Guam and the Northern Marianas Islands are all included
• Official Inland Electronic Navigation Charts (IENC) of U.S. inland waterways are available from the US Army Corps of Engineers at http://www.agc.army.mil/echarts. The download link -> here
• Argentina publishes free raster charts (RNC) for a large part of their coast as well as parts of Antarctica: Argentinian Charts Note that the downloadable "zip" files actually are "rar" files.
• Brazil publishes free raster charts (RNC) for their whole coast and new charts for inland waters are published regularly.There is also coverage for part of Antarctica. Here is a direct link to the download page: Brazilean Charts.
• New Zealand now publishes free BSB3 raster charts, as of 2013-11-22. Download here. NZ has moved away from a proprietary UKHO encrypted format, to the, de facto, standard BSB format. NZ charts cover most of the Pacific in small scale charts, as well as the Southern Ocean, down to Antarctica, South of New Zealand. Detailed charts for the Kermadec Islands, Cook Islands, Niue, Tonga, Western Samoa and the Tokelau Islands, are included.
• The version of the NZ charts compiled by Marco Certelli, includes a better coverage of the Tonga/Samoa area. The official version does not include charts with soundings in fathoms, for example. The link is here.
• The East Asia Hydrographic Commission provides free offshore S57 vector charts for the South China Sea area at: http://scsenc.eahc.asia/main.php. The motivation for releasing these charts is well worth reading.

  Realizing that official and high quality small scale ENCs conforming with the established IHO standard were not available for the SCS, the EAHC MSs decided to cooperate closely and resolve the situation so that mariners could use most up-to-date chart information for voyage planning and enhancing safety of navigation, rather than resorted to some commercially developed electronic products which were either prepared in proprietary formats, or containing unofficial data with very infrequent updating... It was the view that if the SCS ENC could be freely and widely available to mariners, it would further enhance the safety of navigation in the region. This in turn could reduce the chances of environmental damage from grounding and oil pollution, which have tremendous cost impact. The EAHC decided to provide the SCS ENC to users free of charge.

• Colombia and Australia publish sample S57 single charts.
• Many European countries publish free S57 ENC charts for their inland waterways:
  Austria
  Belgium
  Bulgaria
  Croatia
  Czech Republic
  France
  Germany
  Hungary
  Netherlands
  Poland
  Romania
  Serbia
  Slovakia
  Switzerland

• The US Pilot Charts, are available as BSB charts, on the OpenCPN.org download page.
• The OpenSeaMap project publish raster charts in many formats (including KAP which work with OpenCPN). This project relies on mariners to survey their local waters and upload their data using the OpenStreetMap database and editing tools. This project is still in its infancy, so only a few areas have been mapped to any extent. Currently only sea-marks are displayed, but it is planned to include depth & other data in due course. For the maps, go to: openseamap.org

Other Charts

All platforms

• "Antares Charts" are producing a lot of very large scale charts covering "The West Coast of Scotland". These charts are available in many formats, including BSB3. A nominal sum is charged for the charts, to support this impressive effort by unqualified enthusiasts.

Commercial Nautical Charts for OpenCPN

All platforms

• S63 Encrypted ENC charts. Worldwide coverage is available using the latest 3.3 beta version of OpenCPN. These are the official vector charts that big ships use. Detailed coverage of popular cruising grounds is not always available. For details check http://o-charts.org.
• "nv-charts" cover the Bahamas with BSB 3 format charts. Windows is necessary, at least initially, to access the charts.
• 1yachtua.com covers the Mediterranean and the Eastern Caribbean with BSB2 charts.
• The Swedish company "Hydrographica" produces large scale BSB 3 charts for popular areas, based on their own surveys.
• Another Swedish outfit, soltek.se, provides all official charts for Sweden and Finland in BSB 3 format. If you want to buy a CD-area, and don't have access to a Windows computer, contact "soltek" first, as their installation program is Windows only.

Windows only

• The VisitMyHarbour "ChartSticks", are USB sticks covering UK, Ireland, Belgium, Netherlands,Spain and Portugal with UKHO rastercharts. Windows only.
• Windows users also have access to world wide chart-coverage through the "BSB 4" and the "nv-charts" plugins. This coverage includes Europe. UK, for example, is covered by both BA and Imray charts. A simple Internet search will reveal all necessary information.

Links to more chart sources

• A worldwide directory of free available nautical charts can be found on the Website Open Sea Chart. There's a directory for vector charts (http://openseachart.org/doku.php/enc) and a separate one for raster charts (http://openseachart.org/doku.php/rnc). The collection and the updates are community driven.
• Links to a wide selection of ENC's for U.S. inland waters and other countries are available at : http://www.dacust.com/inlandwaters/index.html.

Go to Table Of Contents

Auto Follow and Display Orientation

• Clicking the Auto Follow button will center the chart directly on your vessel's current location. This is a toggle button that is slightly larger and greyer when on. If the the gps is working own ship is red otherwise the icon is gray. . It's also possible that a yellow own ship icon will appear. Read more: GPS Status . Read If zoomed out to a scal that is smaller than 1:300.000 the icons changes to , when receiving gps signals and otherwise. More about he OwnShip icon is available in Marks and Routes.
• The default own ship icon can be replaced by putting a file "ownship.png" in the User icons shared data directory. More about this shared directory here: Marks and Routes
• The Auto Follow button useful for two different situations:

1. When you have panned the map away from your current location and want to quickly move back to your vessel.
2. When underway, this will keep the display on the chart around your vessel, with the boat at the center of the chart.

• Panning the chart will disable Auto Follow mode. Simply click again to turn Auto Follow mode back on. Zooming in/out with the scrollwheel is OK as no panning takes place unless Options->Display->"Zoom-to Cursor" is ticked.
• There are three main options for display orientation, normally it is North Up but Course Up is an alternative. With Course Up OpenCPN uses COG (Course Over Ground). A head Up mode, is not available. The easiest way to change between these two modes is through the "Right Click" menu. One situation where course up might be considered is when navigating a river or a canal. The third orientation is when skew charts are displayed, they are simply shown as "Chart Up", but an optional setting exist to show them as "North Up".
• In the picture below the Course Up is active. COG is 41Deg. Notice how all text on the vector chart, is aligned correctly. This only works in OpenGL mode. The red arrow, in the upper right corner, is always pointing North.

• If the option "Show skewed raster charts as North-up" in the Options->Display->Advanced tab, is not ticked, the right-click toggle option "Course Up Mode/North Up Mode" will be replaced by "Course Up Mode /Chart Up Mode", for skewed charts.
• If an electronic compass is available in the NMEA stream the own ship icon will be orientated according to this heading. The difference can be seen on the chart if there is a cross current, for example. The boat below is heading WNW but is being set SW. An AIS CPA, Closest Point of Approach is also visible.

• This icon (blue color) to the far right in the ToolBar indicates that the display is in North Up mode. It may also indicate Chart Up mode for skewed charts, if chart up mode instead of North up mode i selected. See above
• The red version of the icon indicates Course Up mode. Clicking the icon toggles North Up / Course up. These settings can also be toggled in the rightclick menu, as well as in Options -> Display ->General Tab. In the Options-Display->Advanved Tab, the update period for course up, can be set. This comes in handy, for example, to prevent the display jerking around in a chop.
• The Course Up/North Up icon share a small dialog with the GPS indicator. This dialog can be toggled on/of with the "Ctrl + i" shortcut.
• Note that both the red and the blue arrows are always pointing North.
• Look Ahead! To see more of the chart in front of the boat, activate Options -> Display -> Look Ahead Mode. Your own boat will no longer be in the center of the screen. Instead it will be located away from the center, in the opposite direction to your present gps course(COG).
• Don't always Look Ahead! If you are at anchor, swinging on the hook produces random courses and low speeds.If Look Ahead is on in this situation the chart rendering will constantly be redrawn, with the boat in all possible lookahead positions as the course changes. To prevent this kind of scenario OpenCPN works like this:
  *If the boat speed is less than 1 kt, then lookahead is disabled.
  *If boat speed is greater than 3 kts, lookahead is enabled.
  *In between 1 and 3 kts, the lookahead "distance" is adjusted smoothly.
  *If the problems still there when doing more than 3 kts, consider using "Options->Connections -> FilterNMEA Course and Speed data" to average out the "jumpiness".
• Show skewed raster charts as North-up. Skewed charts are normally showed "chart up", as intended by design. If ticking this box, these charts are shown North-Up. In both cases, activating course up, works as expected, the difference is when course up is not on.
• Full Screen. Enter Full Screen Mode with the F11 toggle. Toggling full scree is also possible through the Menu Bar -> View. Once in full screen mode the Right-Click-menu contains the item "Toggle Full Screen".

Go to Table Of Contents

Tides and Currents

Notes

• Tide and Current predictions are not available for all areas.
• OpenCPN comes with a built in tidal data file, but can use any legacy IDX or binary tcd file. Multiple tidal files can be used at the same time. More about this further down this page.
• As with all predictions, the displayed values are calculated using mathematical models and actual tides and currents will vary

Enable Tides and Currents Display

• Click the toolbar button to see tide stations.
• Select to see current stations.
• Important: tide and currents will not be displayed unless these toolbar buttons are selected.

Displaying Tides

• Available tide stations will show on the chart as green graphs with a "T" logo:
• The "T" becomes a yellow and blue vertical bar when the scale is greater than 1:500.000

• The vertical bar contains a lot of information at a glance.
• The tidal rise is 2.5m above the chart datum. The blue part is "water". The "V" inside he bar indicates that the tide is decreasing towards Low Water.
  
• Here, the tide is rising towards High Water.
• Low Water looks like this.
• High Water Looks like this.
• Right click the middle of either icon to see the tidal graph:

• If a waypoint, route or a track is, or passes, on top of a tidal icon, a right-click will show a context menu for those features. To see the tidal graph, press "Show Tide Information" at the bottom of the menu.

• The Tidal Dialog gives the name of the station as well as the the name of the Data Source file. This is important when you have multiple sources covering the same area. Time and height for HW and LW is displayed in the upper right part.

• The Yellow box, with the tidal rise and time, follows the cursor when hovering over the dialog. The time axis at the bottom displays the time, in this case he timezone is "Z +01:00", which is the same as one hour ahead (east) of UTC, that used to be called GMT.
• In North America it is common to use a three or four letter acronym for timezones.

CODE

UNITED STATES TIME ZONE CODES

UTC OFFSET

AST

ATLANTIC STANDARD TIME

UTC - 4

EST

EASTERN STANDARD TIME

UTC - 5

EDT

EASTERN DAYLIGHT TIME

UTC - 4

CST

CENTRAL STANDARD TIME

UTC - 6

CDT

CENTRAL DAYLIGHT TIME

UTC - 5

MST

MOUNTAIN STANDARD TIME

UTC - 7

MDT

MOUNTAIN DAYLIGHT TIME

UTC - 6

PST

PACIFIC STANDARD TIME

UTC - 8

PDT

PACIFIC DAYLIGHT TIME

UTC - 7

AKST

ALASKA TIME

UTC - 9

AKDT

ALASKA DAYLIGHT TIME

UTC - 8

HAST

HAWAII-ALEUTIAN STANDARD TIME

UTC - 10

HADT

HAWAII-ALEUTIAN DAYLIGHT TIME

UTC - 9

SST

SAMOA STANDARD TIME

UTC - 11

SDT

SAMOA DAYLIGHT TIME

UTC - 10

CHST

CHAMORRO STANDARD TIME

UTC +10

Displaying Currents

• Available current stations will show on the chart as orange diamonds, when zooming in arrows will appear pointing in the direction of the set. Note that "current" here is short for "Tidal Current", and is the same as the UK term "Tidal Stream".
• Master current stations are shown like this in all scales. No direction is associated with these stations but they can be queried, trough a right click, for the magnitude of the current.

• Arrow indicates current direction and strength - the bigger the arrow, the more current.
• The size of the arrows can be customized by users in the opencpn.ini (opencpn.conf) file.
  In the [Settings/Others] section you can set the option CurrentArrowScale to a positive number representing a percentage scaling factor of the current arrows. The values bellow 100 mean the arrows will be smaller than now, the values above 100 will cause them to be bigger.

• A numerical value can be displayed next to the arrow.
• To do this go to Options->Ships->AIS Targets and tick the box "Show names with AIS targets at a scale grater than 1:", and set a scale. When zoomed in to a scale greater than this, the current will also be displayed with a number
• Right click the orange box to see current graph:

• If a waypoint, route or a track is, or passes, on top of a current icon, a rightclick will show a context menu for those features. To see the current graph, press "Show Current Information" at the bottom of the menu.
• The Yelow box, with time,speed and direction, follows the cursor when hovering over the dialog.
• Note that OpenCPN can only display "Reversing Currents" found in restricted waterways, such as rivers and straits. The general case with "Rotary Tidal Currents", can not be displayed with this interface, but are available for some areas as Grib files. More here Grib Weather Plugin .

Using alternative data sets

• OpenCPN supports two tidal file formats. Xtides .tcd file format as well as the default .IDX type. The latter consits of a pair of files called HARMONIC and HARMONIC.IDX, in a directory.
• The default, IDX dataset for tides and currents is limited, mainly for copyright reasons.
• Xtide, a well known free software tidal aplication (GPL license), maintains regularly updated .tcd files for US. Updated files are normally published in December each year. These are presently the only area with, up to date freely available, tidal data. The latest updates are available from the Xtide site, http://www.flaterco.com and ftp://ftp.flaterco.com/xtide/. The "non-free" dataset, including UK and the Netherlands, is no longer updated. The last update was published 2011.
• Please note that OpenCPN differs from XTide results, in very small amounts, usually a few minutes, regarding the times of slack water. This is due to the older algorithm used in OpenCPN compared to the most modern XTides implementation of subordinate station time offset calculation
• There is currently has a problem when multiple .tcd files are loaded. The reference station may be incorrectly identified. In practical navigation only one .tcd file is needed at any given time, depending on which side of the Atlantic you are navigating.
• A number of different datasets are available on the Internet, with vastly greater coverage. Some of these datasets are quite old, and they also contains glitches and errors, many of which have been corrected in the OpenCPN default dataset.
• In many areas there are no free alternatives, and OpenCPN makes it possible to switch between data sets and even using them at the same time. If two stations are located on exactly the same position, only one will be visible......

• Go to Options->Charts->Tides & Currents. Press "Add Dataset.." to add another dataset.
• Tidal files can be located anywhere on your file system, but it will pay off to be organized. The first entry above shows the default location for the built in datafile on Linux. On windows a typical location is "C:\Program Files\OpenCPN\tcdata".

Go to Table Of Contents

Marks and Routes

Marks...

Creating a mark

• Pressing "Ctrl +O" creates a mark at the boats position.
• "Ctrl + M" creates a mark at the cursor position.
• Right-click and and press "Drop Mark" creates a mark, at the position of the cursor, when clicking.
• Marks are created at the start of each leg in a route, and one at the end of the route. More about routes a bit further down this page.

You can move the mark by left-click-dragging it around.

You can delete a mark by right-clicking its icon, and selecting "Delete".
There is an built in undo/redo buffer for creating, deleting or moving marks or waypoints. If you have just created, deleted or moved a mark the right-click dialog will have relevant entries. The undo/redo, for moving or creating marks, follows a straight time-line and is not tied to an individual mark.



Above is a right-click menu just after moving a mark a few times and undoing the last move, and one mark was deleted, and then the deletion was undone. CTRL + Z and CTRL + Y works as hot-keys for undo/redo.

All marks have properties that can be seen by right-clicking and pressing "Properties", or even simpler just double click the mark.
Read all about the properties dialog in Extended Marks
Marks can be manipulated through the Route & Mark Managers Waypoints tab as well. Deleting a mark that is part of a route, will also change the route. Marks that are a part of a "layer" cannot be changed at all. Marks can also be imported into OpenCPN in a number of ways.
Read all about this in the The Route Manager and Gpx Data

A general locking of all marks is available. Goto Options -> Display ->Advanced

and tick the box. This feature is handy, to prevent accidentally moving a mark. Activate this feature when underway, deactivate it when planning.

The Man Over Board mark can be activated through the icon in the toolbar, or through hitting Ctrl + Space-bar. The mark looks like the button and is dropped on own boats present gps position. This mark cannot be moved or deleted with the cursor or keyboard (by mistake), but can still be deleted from the Route/Waypoint manager dialog. More about Man Over Board here.

All the details of the Mark/WP Properties dialog are dealt with in Extended Marks

Use your own Icons

Routes

Press the -button and start the creation of a route. Hotkey "CTRL R" is an alternative way to start a route and "Esc" ends the route. The cursor changes to a ( ) pencil. Left click along the desired route you want to make. This will leave sequential numbered waypoints as you click along, the numbers will not be visible, but are available in the Route Properties Dialog, accessible through the right click menu or the Route Manager. The running total distance of the whole route will be shown along the "pencil" together with the course and distance from the last marked waypoint. When creating routes, OpenCPN will ask if it should use a nearby mark, when a route point is added that is close to an already existing mark. If answering "yes", the existing mark is copied to the route.



For longer distances, specially on east.west courses on higher latitudes, the Create Rout tool seamlessly switches to also offer a great circles alternative, instead of Mercator rhumb-line route legs. Read more Great-circle Sailing.


Holding the cursor over the route brings up a roll-over info. The name of the route, if it is set in the properties dialog, the total length of the route, the course and distance for the leg under the cursor and distance run so far along the route, to the first waypoint in the current leg.
Looking at the four legged route above. The total distance is 8.8 NMi. The third leg is 1.89 NMi i true direction 160° and the accumulated distance in the first two legs is 4.76 NMi.

If your desired route extends off the currently displayed chart, move the route cursor in the desired direction and the display will automatically pan to show the area. You can zoom in and out with the mouse scroll wheel or keyboard +/- keys during route creating. You can also right click and select 'MAX DETAIL HERE' or 'Scale Out' during route creation. When finished right click and choose end route from the context menu, alternatively just press the "Esc" key.
You should now have an inactive (Blue) route. Active routes are Red, inactivated routes are Blue.
Right-clicking on a route brings up a focused menu

Multiple Routes

In OpenCPN multiple routes can be handled in a couple of different ways.
Many routes can be created in a session or imported into a session.
The visibility of every route is controlled in the Route Manager. There is an "eye" to the far left on the line for each route. This works as a toggle switch. A PLAIN Eye means that the route is visible, while an eye with a red cross, means that it's hidden.
This way only the route(s) of interest for the moment can be shown.

Another way is to create and export routes, and later import them when needed.
To keep the chart clear of useful, but not needed routes follow these steps:
• Create a folder called, 'GPX_Routes', or another suitable name.
• Create your route.
• Use the Route Manager to export the route, with a descriptive file name and save it in GPX_Routes.
• Delete the route from the chart.
• You can export all your routes as one big file or export and delete a route as you create them
• When needed, simply use the Route Managers "Import" Button to open the route file.

To get rid of the way points left on the chart when a route has been imported and then deleted, which may happen depending on the imported gpx file.

1. Open the Route Managers Waypoint tab and press the "Delete All" button
2. Say 'Yes' to: 'Are you sure you want to delete <ALL> waypoints?'

Saving and Loading Routes and Marks

• Refer to The Route Manager and Gpx Data to load and save data using The Route Manager

Activating and using routes

• 
• Properties. The dialog is the same as for an individual mark.
• Activate - Gives the direction to the chosen waypoint instead of the first waypoint in the route, which is the default. Useful when joining, for example, an imported route, at an arbitrary waypoint.
• Remove from Route, but don't delete it.
• Copy as kml, for use with Qtvlm or Google Earth.
• Delete Waypoint from Route.
• Send to GPS is seen in the rightclick menus for routes and waypoints. If a port is not selected, the case in the picture above, a dialog is shown to select an output port. To change the selected port, go to the route manager and select "Send to GPS".
• Ctrl + N, a shortcut that activates the next waypoint in an active route.

Autopilots and Routes

Ship Track

Toggling the track icon turns tracking on and off. When tracking is on, the button becomes slightly larger and darker (shown here). Tracking means that a record is kept of the vessels position as it proceeds. A trail is left behind the vessel.
Tracking is persistent. If you shut down OpenCPN with tracking active, tracking will be activated automatically next time you start. Note however that tracking on start up is delayed until a GPS position is available. This action avoids large nonsense jumps in the beginning of the new track.
The way the track is recorded can be set in Options -> Ships -> Ownship.
A full explanation is available in Ownship



Recorded tracks can be imported, exported and managed using the The Route Manager and Gpx Data.

When right clicking on a track you can select Track Properties from the context menu, and a new dialog pops up. Normally it looks like this:



But if the track is a layer or part of a layer, you will see this instead:

A layer cannot be changed easily, and a lot of what follows does not apply to Layer Tracks. Read more about Layers.

The properties dialog can also be reached through the Route Manager. A record of all the track point will be listed. On the screen dump below the tracking precision is set to "Medium". The Waypoints, track points really, appears at irregular times, due to the smart tracking. Only trackpoints that contributes to the track are recorded. In other words, a change in the track occurs at every recorded trackpoint.
Click anywhere on a line in the list of track points, to mark the line and a blue square will mark the position on the track.



From the right click menu the Delete track option is available as well. To prevent mistakes a confirmation dialog pops up.
For more about Tracks read about the Route Managers Track Tab in The Route Manager and Gpx Data.



There ar many options for how a track will be shown and what time to use.
The Advanced tab, were you can document the track and include links, works similar to Extended Marks.

As a backup, a logbook entry is made every half hour in the OpenCPN log file. The format is similar to this:

14:30:00 CEST: LOGBOOK: 2011-06-28 12:30:00 UTC DR Lat 44.43657 Lon -65.17280

Go to Table Of Contents

Man Over Board

MOB activated manually.

MOB activated automatically.

Otherwise.....

Setting Options

Quick links to content of this page.

icon to open the Options Dialog which has 6 tabs, as seen below.
All Settings that are not context sensitive, are set in Options.

Display

The General Tab

1. Keyboard, Menubar, and Toolbar zooms always zoom to center screen. Always.
2. Wheel zoom behaviour changes depending on ZTC (Zoom to Cursor) and SmoothZoom settings.
3. ZTC (Zoom to Cursor) applies only to wheel zooms.

The Units Tab

1. If a GPS receiver that reports variation as part of RMC sentence, is available, this value will be used.
2. Otherwise, if the WMM plugin is installed and activated, it will supply the variation.
3. Lacking the above alternatives, the manually entered "Assumed Magnetic variation", will be used for all calculations. See below.

The Advanced Tab

Use Accelerated Panning works if your graphics card supports Frame Buffer Objects.
Texture Compression greatly improves the speed of raster chart display. It works by treating raster charts as compressed textures instead of bitmaps, and these textures are loaded and displayed much more efficiently by the graphics hardware. They also consume much less GPU memory space.
Texture Compression with Caching A further improvement to raster chart display loading and panning. This option uses the system hard drive to store pre-calculated raster chart compressed images in a way that is optimized for direct loading into the graphics card. When enabled, the texture cache is created dynamically, as charts are visited in normal navigation. Depending on the OpenGL hardware capabilities, there may be some slight, but noticeable, delay as a chart is accessed the very first time while the textures are created, compressed, and written to disk. Once a particular chart section has been cached, subsequent accesses are very fast. If the OpenGL hardware texture buffer is capable, then rendering on-screen is virtually instantaneous.
* The cache understands color scheme changes. Cache entries are automatically created for each of the 4 possible BSB color schemes, as they are encountered in normal operation.
* The cache understands chart Edition Dates. So, if one manually updates a chart (thus changing the chart's Edition Date), the old cache contents will be discarded, and a new cache will be built automatically as the new chart(s) are visited.
* Using compressed texture caching retains all the benefits described earlier. It is very much faster on low spec hardware, at the expense of more disk space usage.
* There is a command line option which will build/update your compressed texture cache. You may execute opencpn like this: opencpn /rebuild_gl_raster_cache (-rebuild_gl_raster_cache on linux)

• * "Texture Compression" and "Texture compression caching" may actually slow down some machines, depending on the capabilities of the video system.
• If you are using OpenGL on a low-spec machine, you will have better performance if you
  a) disable texture caching, or
  b) Pre-build the texture cache in a region of interest. That is, move the boat to say Dover. Then do Options->openGLOptions->Build Texture Cache. You do not need to wait the entire time, which may be hours for a large chart set. "Skip" out when the distance reported is 100 miles or so.
  Eventually, after steady use, your texture cache will be filled automatically in the background, and performance Show FPSwill increase steadily.

The Size of the current "Texture Cache" appears just to the right of the button "Clear Texture Cache". In the picture above this value is 101.8 MB.

• Show FPS FPS stands for Frames Per Second, and is one way measure OpenGL performance. The number appears in the lower right hand corner of the display, to the right of "Scale". Above you see "26 fps". If you report a graphical problem, expect the devolopers to ask you about this figure.

Enable Transparent Toolbar. This option is greyd out in OpenGL mode, as the feature only works in traditional mode. On Linux it is necessary to activate a window manager compositing system, such as Compiz or GNOME Shell, to have a transparent toolbar.
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The Charts Tabs

Chart Files

Vector Charts

Read more about Vector Charts !

Chart Groups

Tides & Currents

The Connections Tab

The Ships Tabs

Own Ship Tab

1. The "normal range" is less than the declared arrival radius.
2. Ownship is moving away from the target waypoint, and has been for more than two seconds.

AIS Targets Tab

MMSI Properties Tab

Add a new target to track.

The User Interface Tab

Change Font Color to suit your taste.

The Plugins Tab

Data Connections

Linux Serial Connections

Make sure that you belong to the "dialout"* group. To find out, run the "$groups" command. If you're not in "dialout", add yourself with the command "$sudo usermod -a -G dialout $USER". Check this straight away, it will save you from frustration later on. If there is a problem connecting the GPS to a physical port, such as /dev/ttyS0, the reason is probably that you don't belong to "dialout". OpenCPN will display a warning, once per session, if you try to configure a serial connection, or starts the program with an active serial connection, and don't belong to the right group. * Red Hat based Linux versions are using the "uucp" group. Check what applies to your version of Linux, by using the return from the command "stat -c %G `ls /dev/*|grep -m1 tty[A-Z,a-z][0]`" If the return is "root", upgrade to a contemporary Linux version.

• All this is different from the logic in earlier versions of OpenCPN. From version 3.2, there is no defined "autopilot" port. The autopilot is simply connected to any available output- enabled data-stream, and gets everything on the bus, subject to user specified output filtering. There is no specific "shared" AIS and GPS port, as all ports are shared.

• The key point to keep in mind with this new setup is the complete orthogonality between message sources, message destinations, and transport media. All messages come and go from an internal "bus", and all internal modules have access to all messages. Any message can be received, and possibly re-transmitted according to the configuration established. If the messages get onto the bus, OpenCPN will do the right thing. For example, if it is an AIS message, the AIS module will get the message and act accordingly. Plugins also get all messages.

• To get a taste of what can be done, we start with a lab scenario. In the screen-shot above, four Data Ports are enabled. GPSD on localhost port 2947, /dev/ttyUSB1 as ais port, next is an output port to a computer on the local network and last the San Fransisco AIS feed *. Note that the connections are automatically sorted in order of the priority setting The picture is from a Linux computer, but the receiving box is an Win XP. Both boxes are configured to use the same broadcasting address 192.168.0.255 ** on the local network, using the default 10110 port. Note that UDP, and not TCP, is used. OpenCPN on the XP box receives and shows all info from the three first ports and even data from the VDR plugin, if it's running. All input sources are merged together and available to transmit to an external computer. Every computer on-board can be used as a repeater to the main box!
• Note that in this scenario the UDP connection is output only. In previous releases of OpenCPN all UDP data connections would read data as well as write. This is a possible configuration in the current release but neither required nor generally desirable. If a broadcast connection is read/write, all data written will be read back leading to the potential for data loops. To avoid this, the priority of any read/write broadcast connection should be set lower than that of any other interface on which OpenCPN receives data for re-distribution over that interface. For most purposes setting a broadcast connection to either read or write is the preferable solution.

• In real life, a common setup will include input from GPS, AIS and output to an Autopilot. If your GPS produces GPRMC, then this will be automatically shipped to the autopilot. Everything on the internal multiplex bus will be sent to the output port that the autopilot is connected to, even if a route is inactive. If, a route is active, OpenCPN will create and send NMEA (EC)RMC sentences to output data ports. The only reason OpenCPN "synthesize" an ECRMC sentence is to cover those odd cases when there is no other source of RMC in the system, and the Autopilot wants variation, SOG, etc. This might be the case if an older GPS produces GPGLL alone, for instance, which has no var. There is no "new" information in the transmitted, synthesized ECRMC.
• The autopilot might be complaining that it is getting RMC information from two different talkers (GP and EC) at the same time, and cannot decide what to do. The easiest solution if don't like the ECRMC, is to filter it out of the output stream of the port connected to the autopilot. Or choose a filter to allow only GPRMC and ECRMB for this port.

• Filter NMEA Course and Speed Data: Providing a rolling average of COG/SOG, with configurable sampling period. This feature is useful, for example, if you find that course and speed from the gps is varying erratically due to the sea state. The Dashboard plugin is not affected by this setting - COG and SOG are updated about once per second.

• Show NMEA Debug Window: If you check this box you will get a window that shows the NMEA data sentences coming into or going out from OpenCPN. In the picture above we can see the color-coding at work. Messages in red could occur as well, and indicates a transmit error. Connections Priority change messages, will also be printed to the NMEA Debug Window. The reason that AIVDM messages are both dropped and appear as "Output message", is that there is more than one source for this message, and the filter just applies to one source.
• Have a look at the page NMEA Sentences to see which messages are understood. OpenCPN generally does not care about the Talker ID, the first two letters in the message type. $GPGGA above, is the talker GP = the gps, sending a GGA = position message, for example. At the end of each sentence there is a "*" followed by a calculated checksum.
• To see all messages it's important to close the Options dialog completely, while leaving the NMEA Debug window open. The ECAPB sentences etc, will not appear while the Connections dialog box is open as autopilot output is disabled during this time.
• Known issues: The pause button only works if the main Options dialog is closed. In Linux, the debug window can only be closed by unticking the Show NMEA Debug Window box, unless the the main Options dialog is closed.

• If there are NMEA sentences in the debug window, then OpenCPN has opened the port set in the Data Connections. Note that the source of each NMEA sentence is printed after the time stamp o each line. If your GPS port is configured, and there is no "red" boat, then the only reasons are: no gps fix or wrong sentence configuration from the GPS.
• Messages originating from GPSD or the VDR (Voyage Data Recorder plugin) will also show up in the debug window.

• For simple NMEA data stream debugging, add the following to your opencpn.ini file:Under [Settings] add a line

• Format uploads for Furuno GP3X input filtering: If the special Furuno gps protocol is needed, tick this box. The reason is that Furuno uses their own version of NMEA for uploading routes. Furuno GPS users take note. It is now allowed to use a numeric, two digit OpenCPN route name (e.g. 10, 21, etc).

• Use Garmin GRMN (Host) mode for uploads. Make sure that this box is ticked, if you have a Garmin GPS. The reason for this is that Garmin units cannot accept route uploads via standard NMEA0183. This is a "design feature" of all Garmin receivers.
• Use magnetic bearings in output sentence ECAPB. Some autopilots, among them Simrad, require navigational bearings, contained in the APB sentence, to be transmitted as Magnetic bearings rather than as True bearings, OpenCPNs default.

Data Connections

• Two Buttons "Add Connections" and "Remove Connections", to the right of the Connections window are the key to this whole tab.
• The enable choice at the start of each connection line, is handy to organize connections, but still only use those that are needed for the moment. Tick or un-tick, and then press "Apply", to activate the setting.
• A connection can be used for input and output at the same time, with the reservation that they have to use the same Baud rate. For more details, read on.
• When pressing "Add Connections" two basic choices are given, a serial or a network connection.

Add a Serial Connection

• DataPort: Pick a port by pressing the \/ o the right side of the field. If the port you are looking for does not appear in the selection, write the correct port yourself in this field.

• Baud Rate: This is normally 4800 for GPS and 38400 for AIS, but check the documentation for the connected device. It's important to get this right and not just guess.

• Protocol: For future use, as only NMEA 0183 works, for now.

• Priority: Higher number equals Higher priority. The priority is set for each NMEA sentence individually. As long as a higher priority stream is available it's used. If this fails the next stream in line, with lower priority, kicks in and is used, until a higher priority stream appears. The present filter does not handle the case where, for example position messages, are received from different sentences.As an example, GPGLL and GPRMC both transmits the position information. The last received of either message will be used.

• Control Checksum. At the end of each NMEA sentence is a checksum, that makes sure that sentences are correctly received. This box is ticked by default, as OpenCPN calculates the checksum and compares it to the received checksum. Only sentences with a valid checksum are passed through. Un-ticking may help, if an application calculates checksums incorrectly or if the checksums are missing.

• Use Garmin (GRMN) mode for input: Make sure that this box is ticked, if you have a Garmin GPS set to this mode. The reason is that Garmin uses their own serial protocol.
• Receive input on this Port Greyed out here as it only applies to a network connection. see more below.
• Output on this port (as Autopilot or NMEA repeater ): Tick this box if the connection will be used for output. A common case is sending NMEA to an Autopilot.
• APB bearing precision is greyed out unless "Output on this port" is checked. APB is the NMEA sentence "Autopilot Sentence 'B'". The precision can be set to between 0 and 4 decimals, were 3 is the default. Some autopilots requires a different precision than the default, to work. Check your AP documentation.
• Note that the "XTE - Measured cross track error" NMEA message, that is a part of the APB message is not adjusted by the APB bearing precision setting. It is however possible to set the precision of the XTE through the opencpn.ini / opencpn. conf file. Add a line

Add a Network Connection

• Protocol: There are three choices of protocols TCP, UDP and GPSD.

• TCP: is a "connection-oriented" protocol which provides a reliable link between two network endpoints. TCP ensures that any network packets lost in transit are re-transmitted. Internet AIS servers normally accept TCP connections as do many serial-to-network/wifi devices.
• To make a connection to a remote TCP server, enter its IP address or hostname in the "Address" box and the TCP port on which the server listens in the "DataPort" box. Many devices use a non-standard TCP port rather than OpenCPN's standard 10110, so do check the server's documentation.
• If "0.0.0.0" is entered in the "Address" box, OpenCPN will act as a TCP server accepting a connection from a remote TCP client. OpenCPN will listen on all its host computer's network interfaces for TCP connections to the port specified in the "DataPort" field. There should normally be no reason to select a "DataPort" value other than the standard 10110 unless multiple servers are required: In the current implementation a single data connection can accept only one client. If multiple clients wish to connect to OpenCPN, a dedicated data connection must be provided for each and each data connection must have a different DataPort.

• UDP: is a method of transmitting data as simple "datagrams" without negotiating a connection between two endpoints. It involves no detection and retransmission of data lost in the network. Within a small home/boat network such data loss should not normally occur and in any case, NMEA data is generally updated by "talkers" on a regular basis. Unlike TCP which involves a connection between two endpoints, UDP data may be received by many "listeners".
• An OpenCPN UDP data connection will listen for data destined for the specified DataPort on any system interface or the broadcast address of any connected network. If you don't need to receive multicast data or transmit any data, you may enter "0.0.0.0" in the "Address" box if you are unsure of what to enter there. Alternatively you may specify the address on which you intend to receive data. In both cases behavior will be the same. If you wish to receive multicast data you must enter the multicast address to which those data are being sent or the system will not see them. If you wish to transmit any data ("Output on this port" checked) you must put the address you wish to send data to in the "Address" box. In all cases (transmit, receive or both) the DataPort must be specified. For more information about broadcast and multicast, see "Broadcast and Multicast" below.
• GPSD: is a Unix/Linux gps server, which means that several different applications can share one gps receiver. Linux users have the choice between using serial or GPSD connections for their gps input.
• Ubuntu users take note! If gpsd is installed - use it. If you prefer a serial connection, un-install gpsd. The reason is that gpsd starts automatically when,for example, an USB gps is connected. This will block the serial port that the gps communicates with( /dev/ttyUSB0 in many cases), hence no separate serial connection to the gps is possible. So it's an either or situation.
• OpenCPN also has support for Windows clients. So a windows computer should be able to connect to GPSD running somewhere on a network (testing), as an alternative to an UDP connection, described earlier.

• Address: The network address to connect to. In the example above we used the broadcast address for convenience, but specifying host to send to, and host to receive from, works as well.

• Port: The port to connect to on the network address. The default port for UDP is 10110. Port 10110 is designated by IANA for "NMEA-0183 Navigational Data". There should not be any reason to change this port, but it is possible. See below. The default port for GPSD is 2947. Do not change this!
• For your own local connections use port-numbers greater than 1023 and avoid ports used by other applications. Ports in the range 49152 through 65535 are not assigned to other applications and should be OK. Make sure that no firewall is blocking the port you pick.

Network GPSD connection

• When connecting to GPSD, running on your local computer, use the settings shown above.

Connections Filter

• For each source line in the data connection windows, it's possible to specify exactly which NMEA sentences to receive, and which ones to drop. Similarly it's possible to control exactly which sentences to send out to, for example, an autopilot.
• The applied filters for each connection are stated in in the "Filters" column in the Data Connection window. The default for a connection is no filters at all.
• Filtering can be observed in real time, through color coding in the Debug Window.

• Accept only sentences: Either base your filtering on stating which sentences to accept or which to ignore.
• Ignore sentences: Same as above.
• To select filters press the button. The dialog below becomes available.

• A lot of NMEA sentences are listed. Just tick the box to select a sentence. "Select All" or "Clear All" are also available.
• For sentences not listed press "Add", and enter a new NMEA sentence.

• Your entry must conform to these rules.

• When you are finished, press "OK", your new entry will appear at the bottom of the list of NMEA sentences to filter. It will already be ticked, so just press "OK" until you are back in the original Connections tab. Now press "Apply". The implemented filtering should now be visible on the connection line. For more, see below

• Receive input on this port: This box should be ticked if you want to receive receive data on this connection. If the connection will only be used to output to other devices it should not be ticked. If you wish to broadcast UDP data for consumption by other devices or programs, leaving this box unticked will save you having to worry setting the priority of the connection to avoid data loops.
• Output on this port (as Autopilot or NMEA repeater ): Tick this box if the connection will be used for output. A common case is sending NMEA to an Autopilot.
• APB bearing precision is greyed out unless "Output on this port" is checked. APB is the NMEA sentence "Autopilot Sentence 'B'". The precision can be set to between 0 and 4 decimals, were 3 is the default. Some autopilots requires a different precision than the default, to work. Check your AP documentation.
• OpenCPN creates and sends the NMEA ECRMB and ECRMC sentences to the A/P output port when a route is activated. If variation is not otherwise present, OpenCPN includes variation, coming from the WMM plugin, if installed and enabled.

• Some examples to illustrate how things works.

• Similar to input filtering above.

Connection Notes

• If you already have an application connected to your gps, on a serial port, OpenCPN will not be able to connect to the same port. Two applications cannot use a port simultaneously. On Linux use Gpsd in such a situation. Of course this only works if your "other application" supports the Gpsd. As an alternative on Linux you can use Kplex (also for Mac) or Muplex which can create pseudo terminals ("virtual serial ports") to share NMEA data between applications.
• If a NMEA sentence is filtered on an input connection and "LegacyInputCOMPortFilterBehaviour=1" setting in opencpn.conf|ini, it will still enter the internal multiplexer. So, it will be available to output connections, unless it's filtered there as well. If "LegacyInputCOMPortFilterBehaviour=0" then the message will not be placed on the internal multiplexer. This will only work for serial connections. Echoing back a network connection, on the input port for output, will not work
• NMEA data can also come from the VDR plugin. They will be labeled as such in the Debug Window and have "0" priority.

Sending an Active Route to an Autopilot

• On Route activation, OpenCPN sends the ECRMB, ECRMC and ECAPB NMEA sentences to an Auto Pilot, if it is connected to a port, with output activated.

Broadcast and Multicast

• UDP data may be delivered to more than one system when sent to certain special addresses
• A "broadcast address" is listened to by all devices on a network. It is normally formed by taking the network address (the first part of the IP address common to all systems on your local network) and setting the last part (the number which is different for every computer) to a value represented by all "1"s in binary. If all your devices' addresses start with "192.168.1", your network's broadcast address will likely be 192.168.1.255 (255 is "11111111" in binary. This is why IPv4 addresses written like this never contain numbers higher than 255. Except for in the movie "The Net" and we don't talk about that). If you specify an address ending with "255", OpenCPN assumes you mean a broadcast address. This is not always true but will result in desired behaviour in almost all cases.
• The special broadcast address "255.255.255.255" is also listened to by all devices. It should not normally be used to transmit data from OpenCPN. Use your local network's broadcast address instead.
• A "multicast address" is listened to only by devices which wish to receive information on that address. IPv4 addresses in the range 224.0.0.0 - 239.255.255.255 are multicast addresses. If you specify a multicast address for a UDP data connection, OpenCPN will tell your computer to listen for datagrams on that address.
• More than one system may send data to broadcast or multicast addresses, so this is a "many to many" communications medium.
• You cannot use broadcast or multicast addresses with TCP. TCP is a "one to one" connection.
• Devices must to some extent process all broadcast packets on the network whether they are interested in them or not. Multicast packets are normally only seen by devices which have registered an interest in a particular multicast address. Consequently multicast is more efficient than broadcast although this is usually of little consequence in a small network. Despite being used by NMEA-over-IP protocols such as IEC 61162-4 and the forthcoming NMEA OneNet, NMEA-0183 over IP multicast is far less widely supported in marine applications than NMEA-0183 over IP broadcast.
• There is no multicast address mandated for NMEA-0183 data in this context although you should avoid those addresses used by other protocols. When using multicast with OpenCPN it is suggested that an address be used in the range 239.192.0.0/14 specified by RFC 2365 as the "Organization Local Scope". If in doubt, try 239.194.4.4.
• There is no mechanism in OpenCPN to specify the network interface through which multicast packets are sent or received. This will be determined by your system. In some cases it may be necessary to manually adjust your system's routing table to ensure that the desired network interface is used. Refer to your system's documentation if this proves necessary.
• If you transmit UDP broadcast or multicast, then you should set the priority of the "real" NMEA input to something higher than the UDP stream. If not, prepare for problems. The reason is that if you are broadcasting, then you yourself will get the UDP message as well, which again will be retransmitted...... Obviously, it duplicates the "real" incoming data. Thus we get source priority flip-flop on each message, since they have the same priority. For example set the UDP priority to "0" and real incoming connection to "1" or higher. Multicast loopback is not disabled for consistency with broadcast behaviour. This means that priorities must be set as detailed above when transmitting over multicast, but multicast communication between multiple instances of OpenCPN on the same system remains possible.
• The firewalls on some systems (e.g. OpenSuSE linux) may block broadcast and multicast data that you wish to receive. Refer to your system's documentation to determine how to allow such data to reach OpenCPN.

Sending Routes and Waypoints to a GPS

• The feature "Send to GPS", which appears in the right click menus for waypoints and routes and in the Route Manager, is not linked to connections. The upload port does not even need to appear in the Datastream connections list. Its a completely separate concept. For this reason users must define a separate upload port, that is remembered by OpenCPN. The port can be changed by clicking the button in the Route Manager.
• NMEA provides no handshake protocol for Route and Waypoint upload. So, OpenCPN simply sends the Route/WP information out on the port, without having any way to know if there is actually a device connected to the port.
• The Garmin protocol does provide handshaking, so OpenCPN can be sure that the information is uploaded correctly. The Garmin protocol will fail if the device is not a Garmin.
• In the case of standard NMEA, the indication "Route successfully uploaded"
  is not very meaningful. You can say that it just means that a port was found,
  and writing to that port succeeded.
• In the case of "hockey puck" GPS receivers, they probably ignore Route and WP uploads, since there is nothing for them to do with this information anyway.
• The key to remember is that Route and Waypoint upload process is completely independent of normal running Datastream operation. They are two separate sub-systems.
• It does no harm to assign the Datastream GPS port as an output and input device together. Some users might reasonably expect that this would be required for Route and W/P uploads. Most GPS receivers would ignore input sentences other than Route and W/P uploads anyway.

NMEA Sentences

For a comprehensive explanation of the NMEA protocol please read http://www.catb.org/gpsd/NMEA.html

OpenCPN Recognized NMEA Sentences:

The Core Program:

• HDM - Heading, Magnetic

1. Heading Degrees, magnetic
2. M = magnetic

• HDG - Magnetic heading, deviation, variation

1. Magnetic Sensor heading in degrees
2. Magnetic Deviation, degrees
3. Magnetic Deviation direction, E = Easterly, W = Westerly
4. Magnetic Variation degrees
5. Magnetic Variation direction, E = Easterly, W = Westerly<

• HDT - Heading, True

1. Heading Degrees, true
2. T = True

3. RMB - Recommended Minimum Navigation Information

   To be sent by a navigation receiver when a destination waypoint is active.

                                                                14
           1 2   3 4    5    6       7 8        9 10  11  12  13|  15
           | |   | |    |    |       | |        | |   |   |   | |   |
    $--RMB,A,x.x,a,c--c,c--c,llll.ll,a,yyyyy.yy,a,x.x,x.x,x.x,A,m,*hh<CR><LF>

   Field Number:

   1 Status, A= Active, V = Void
   2 Cross Track error - nautical miles
   3 Direction to Steer, Left or Right
   4 TO Waypoint ID
   5 FROM Waypoint ID
   6 Destination Waypoint Latitude
   7 N or S
   8 Destination Waypoint Longitude
   9 E or W
   10 Range to destination in nautical miles
   11 Bearing to destination in degrees True
   12 Destination closing velocity in knots
   13 Arrival Status, A = Arrival Circle Entered
   14 FAA mode indicator (NMEA 2.3 and later)

• RMC -Recommended Minimum Navigation Information

1. Time (UTC)
2. Status, V = Navigation receiver warning
3. Latitude
4. N or S
5. Longitude
6. E or W
7. Speed over ground, knots
8. Track Made Good, degrees true
9. Date, ddmmyy
10. Magnetic variation, degrees
11. E or W
12. *

• xxWPL - Waypoint Location Used to send routes and waypoints up to a GPS receiver. OpenCPN does not process these sentences as input.

1. Latitude
2. N or S (North or South)
3. Longitude
4. E or W (East or West)
5. Waypoint Name

• xxRTE - Routes. Used to send routes and waypoints up to a GPS receiver.OpenCPN does not process these sentences as input.

1. Total number of messages being transmitted
2. Message Number
3. Message Mode
   1. c = complete route, all waypoints
   2. w = working route, the waypoint you just left, the waypoint you're heading to, then all the rest
4. Waypoint ID
5. More Waypoints

• GGA - Global Positioning System Fix Data

1. Universal Time Coordinated (UTC)
2. Latitude
3. Longitude
4. GPS Quality Indicator
5. Number of satellites in view, 00 - 12
6. Horizontal Dilution of Precision (HDOP)
7. Antenna altitude above/below mean-sea-level (geoid)
8. Units of antenna altitude, meters
9. Geoidal separation, the vertical difference between the WGS-84 elipsoid and the geoid
10. Units of geoidal separation, meters
11. Age of differential GPS data, time in seconds since last SC104
12. Differential reference station ID, 0000-102

• GLL - Geographic Position, Latitude / Longitude

1. Latitude
2. N or S (North or South)
3. Longitude
4. E or W (East or West)
5. Time (UTC)
6. Status A - Data Valid, V - Data Invalid
7. *

• GSV - Satellites in view

1. Number of sentences for full data / sentence 1 of 2
2. Number of satellites in view
3. Satellite PRN number
4. Elevation, degrees
5. Azimuth, degrees
6. SNR - higher is better / for up to 4 satellites per sentence

• VTG - Track Made Good and Ground Speed

1. Track Degrees
2. T = True
3. Track Degrees
4. M = Magnetic
5. Speed Knots
6. N = Knots
7. Speed Kilometers Per Hour
8. K = Kilometers Per Hour
9. *

• GPwpl - Waypoint data, only when there is an active route (this is sometimes bidirectional).

• APB - Autopilot Sentence "B" This is a fixed form of the APA sentence with some ambiguities removed.

  Note: Some autopilots, Robertson in particular, misinterpret "bearing from origin to destination" as "bearing from present position to destination". This is likely due to the difference between the APB sentence and the APA sentence. for the APA sentence this would be the correct thing to do for the data in the same field. APA only differs from APB in this one field and APA leaves off the last two fields where this distinction is clearly spelled out. This will result in poor performance if the boat is sufficiently off-course that the two bearings are different.

  Field Number:

  1 Status V = LORAN-C Blink or SNR warning V = general warning flag or other navigation systems when a reliable fix is not available
  2 Status V = Loran-C Cycle Lock warning flag A = OK or not used
  3 Cross Track Error Magnitude
  4 Direction to steer, L or R
  5 Cross Track Units, N = Nautical Miles
  6 Status A = Arrival Circle Entered
  7 Status A = Perpendicular passed at waypoint
  8 Bearing origin to destination
  9 M = Magnetic, T = True
  10 Destination Waypoint ID
  11 Bearing, present position to Destination
  12 M = Magnetic, T = True
  13 Heading to steer to destination waypoint
  14 M = Magnetic, T = True

  
  

XTE - Measured cross track error Measured cross track error is a part of the RMB message, for compatibility with some older equipment designed to work with Loran.

1. Cross track error, measured
2. General warning flag V = warning
3. (Loran-C Blink or SNR warning)
4. Not used for GPS (Loran-C cycle lock flag)
5. Cross track error distance
6. L - Steer left to correct error (or R for right)
7. N- Distance units - Nautical miles

• AIVDM - Automatic Information System (AIS) position reports from other vessels

1. Time (UTC)
2. MMSI Number
3. Latitude
4. Longitude
5. Speed Knots
6. Heading
7. Course over Ground
8. Rate of turn
9. Navigation status

• AIVDO - Automatic Information System (AIS) position reports from own vessel

1. Latitude
2. Longitude
3. Speed over ground
4. Course over ground
5. MMSI, navigational status, ship type, call sign, destination, sizes (in AIS target list)

• xxTTM - Tracked Target Message

1. Target Number (0-99)
2. Target Distance
3. Bearing from own ship
4. Bearing Units
5. Target Speed
6. Target Course
7. Course Units
8. Distance of closest-point-of-approach
9. Time until closest-point-of-approach "-" means increasing
10. "-" means increasing
11. Target name
12. Target Status
13. Reference Target

• xxTLL - Target Latitude and Longitude

1. Target Number (not used/ignored)
2. Latitude
3. Longitude
4. Name
5. Status
6. Reference Target (not used/ignored)

• xxOSD - Own Ship Data

1. Heading, degrees true
2. Status, A = Data Valid
3. Vessel Course, degrees True
4. Course Reference
5. Vessel Speed
6. Speed Reference
7. Vessel Set, degrees True
8. Vessel drift (speed)
9. Speed Units

FPROS - GPSGate Buddy Position Update.

1. Latitude
2. Hemisphere N/S
3. Longitude
4. Hemisphere E/W
5. Altitude in meters above sea level
6. Speed over ground in knots
7. Heading over ground in degrees
8. Date
9. Time UTC
10. Name of buddy this position info belongs to.

• CDDSC - Digital Selective Calling Information
• CDDSE - Extended Digital Selective Calling Information, including a more accurate position.

For more details on how OpenCPN interprets all recognized sentences, look at the "AIS_DecoderA.cpp" file in the source code. For the Dashboard plugin, look at the different files in the "nmea0183" directory.

The Dashboard Plugin recognises the following input NMEA sentences:

• DBT - Depth Below Transducer
• DPT - Depth of Water
• GGA - Global Positioning System Fix Data
• GLL - Geographic Position - Latitude/Longitude HDG Heading - Deviation & Variation
• HDM - Heading - Magnetic
• HDT - Heading - True
• MTA - Air Temperature (obsolete)
• MDA - Meteorological Composite (obsolete)
• MTW - Mean Temperature of Water
• VLW - Distance Traveled through Water
• MWD - Wind Direction & Speed
• MWV - Wind Speed and Angle
• RMC - Recommended Minimum Navigation Information
• RSA - Rudder Sensor Angle
• VHW - Water speed and heading
• VTG - Track made good and Ground speed
• VWR - Relative Wind Speed and Angle
• VWT - True Windspeed and Angle (obsolete)
• ZDA -Time & Date - UTC, day, month, year and local time zone
• AIVDO - Automatic Information System (AIS) position reports from own vessel

^*
NMEA version 2.3.added a mode indicator to many sentences to indicate what
kind of fix the receiver has. The value can be one of
A=autonomous
D=differential
E=Estimated
N=not valid,
S=Simulator.
Sometimes there can even be a null value as well.
The A and D are the only vales that will indicate an Active and reliable Sentence.
This mode character has been added to the end of RMC, RMB, VTG, and GLL sentences.
Optionally, to some others as well, including the BWC and XTE sentences.

Go to Table Of Contents

GPS Status

AIS

For a general introduction to AIS, Wikipedia is a good place to start.
The screen-dump below gives you a first feel for how AIS targets are presented and used in OpenCPN.



The Lookahead mode is activated here and our own vessel is proceeding 352 deg at 13.8 kts, leaving an activated track behind, and projecting a dashed line ahead representing the course. This ends in a dot, that represents where we will be in 6 minutes, or 1.38 nautical miles ahead. We are meeting a vessel, steaming in the opposite direction following the traffic separation. This target also has a line and a dot in-front of it representing course and where it will be in 6 minutes(user configurable), and a track behind it.. The two blue dots with a red/yellow line between them, represents where the vessels will be at CPA - closest point of approach, or when the are nearest each other, with present courses and speeds. The meeting vessel is red, as it is a potential danger to us. An AIS target alert dialog has just popped up.

There is a lot of information about the vessels that transmits AIS signals.

The cursor is on top of the the meeting vessel on a SW course. As we have not yet received full information, this can take a while, we don't get the name but an id number, the so called MMSI number, instead. Exactly what is shown in the yellow pop-up is configured in the AIS tabs Rollover heading.

This vessel is identified by name, and has a green color, as it does not represent any danger to our navigation.

AIS Target Query

If we instead of just hovering the cursor on an object, double click it, the dialog above pops up. A lot of relevant information is displayed. CPA, "Closest Point of Approach", to ownship is 12.7 miles in 12min 57s.
More information about the target itself, is available on Internet address: http://www.marinetraffic.com/ais/shipdetails.aspx?mmsi="MMSI number here", in this case: http://www.marinetraffic.com/ais/shipdetails.aspx?mmsi=233150000

Buttons in the Target Query Dialog

Create Waypoint drops a mark at the targets current position.

Record Track/ Stop Recording
Pressing the "Reckord Track" button brings up a new dialog



The recently recorded track of the "Poseidon Leader" will appear in the Route & Mark managers track tab on a line starting with "AIS Poseidon Leader.....".
If the "Yes" button is pressed, the Target Query Dialog button ""Record Track" changes to "Stop Recording". All tracks recorded will behave just like any other track.






Right-clicking a target brings up a dialog focused on AIS.

Aids to Navigation AtoN

More and more aids to navigation are equipped with an ais transmitter, and shows up as a target in OpenCPN like this


Note the word "Real", that says that this is an object that exists in reality.


Here we have an AIS transmitter on a floating W Cardinal Mark.
This is of course real and the buoy is on position. If the buoy is off position, for some reason, the Aton icon becomes red.


There are also Virtual AtoNs marked with their own icon .
Virtual AtoNs are used to quickly make mariners aware of things like new wrecks, uncharted hazards and floating debris. They are normally used for a short duration until replaced by real buoy, charted, removed or dispersed.

Virtual AtoNs are also used for information. An example...the position of the Italian Maritime Rescue Coordinating Center. Note the word "Virtual" in the dialog.

AIS update rate.

How often are the AIS information updated from each target?
The required update rates from an AIS target transmitter is shown below.

The AIS Target List

AIS Transponder and Ownship.

OpenCPN does not show the ownship (i.e. AIVDO message) neither as an AIS target, nor in the target list. AIVDO is processed only in the main navigation thread.
Earlier releases did show ownship, but this was a bug, simply an illusion.
The earlier presence of AIVDO (ownship) information in the data stream, really only indicated that the transponder was turned on and received GPS signals. The only true way to monitor the output of a transponder, is with a separate AIS receiver.

AIS data port

Select your AIS input port in the Connection Tab. The AIS button in the ToolBar, appears different according to the following conditions.
AIS Alive. The default AIS button. This icon appears as soon as an AIS port is active in the tool-box. It is also the normal state with an AIS receiver working and with no targets of interest.

AIS Alive and Activity, a small green circle will illuminate in the lower right corner of the Ais buton. If there is at least one AIS message every 4 seconds, the light will remain illuminated.

AIS Suppressed. This icon indicates only that target suppression is activated in the AIS tab in the ToolBox. Referring to the picture above there are two sort of suppression:
* Suppress display of all moored/anchored targets, max speed specified in dialog.
* Suppress Alerts for moored/anchored targets.
This icon will be over-ridden with the AIS alarm button if an alarm is, or becomes, active according to the AIS tab alarms settings in the toolbox.

AIS Alarm. A target exist that raises the alarm as defined in the AIS tab in the ToolBox. It is the three settings "CPA Calculations", that rules if and when an alarm is raised.

AIS Disabled. No targets, if available, are shown on the screen. This button toggles with the other buttons. For example, if the AIS alarm button is visible, click the button and it will change to the "AIS Disabled" button, and all targets, alarms etc, disappears from the display. Click again and the original button and AIS display comes back.

The ToolBox AIS Tab

This tab controls the behavior of many thing in the AIS display. There are no "best" settings. It all depend on where you are, what kind of navigation you are into and what kind of vessel you are on. It is your responsibility to evaluate this.

CPA calculation: Rules for when the Closest Point of Approach- CPA (when two vessels are nearest each other) and the Time For Closest Point of Approach (TCPA) is calculated, and when warnings are activated.
There are three tick boxes, which can be activated with user set values.

No CPA Calculation if target range is greater than (NMi)
If the vessel is far away it is less interesting to calculate CPA. In a busy waterway this could cut down on clutter and processing speed if a reasonable value is set.
Warn if CPA is less than(NMI)
Similar arguments to No 1. This controls when a warning for minimum CPA distance is given. A warning can be both on the screen and a sound. The CPA is shown on the screen when a warning is active.
..and TCPA is less than (min)
This Box can only be activated if the previous box is active. If the minimum CPA is far in the future, it's not so interesting. If it's hours away, both vessels have probably changed speed and course in the meantime. Set TCPA to a reasonable value value depending on circumstances. A lower value if negotiating a busy waterway. A higher value when offshore. Many factors plays a role here. If you need to get off watch crew up on deck for a manoeuvre, take this into account, for example. Do you find that you get to many useless alarms? Consider lowering this value and/or the CPA value.

If a target is within the distance set in #1 and without an active warning, theCPA can be shown anyway through right-clicking on the target.



"Show Target CPA" toggles with "Hide Target CPA"

More About Target CPA, a few more tricks are available.

Lost Targets: Rules for how lost targets should be handled on the display.

Mark Target as lost after (min)
Target is regarded as lost if no transmission are received for the number of minutes set here, the target will change on the display and have a black bar across.
Remove lost targets after (min)
The lost target will be removed from the display after the number of minutes set here.

Display: If and how a vessels course and speed should be displayed and if stationary vessels should be on the screen.

Show target COG predictor arrow, length (min)
An arrow will be shown in front of the vessel representing it's COG (Course Over Ground). The length of this arrow and the dot at the end of it represents the calculated position in the number of minutes set here. Set easily calculated values. If a vessel approaches you doing 15 kts and the time is set to 6 minutes, the dot will be 1.5 nautical miles ahead of the vessel.

To track or not to track?

This choice below boils down to two basic scenarios.

• All targets will be tracked, with the option of turning off tracks for selected targets.
• No targets will be tracked, with the option of starting to track selected targets

Show target tracks, length (min)
This is the basic setting that can be refined in the "AIS Target list". With this box ticked targets are tracked even if they are not displayed. Start out with this option ticked, if you hesitate. Come back and fintune the settings later on, if necessary.

A track will be shown behind a target. This helps to judge the target vessels intentions.



When this option is ticked, the context sensitive AIS menu changes to include the toggle option "Hide Target Track" / "Show Target Track".



When this option is not ticked, the context sensitive AIS menu changes to include the toggle option "Show Target Track" / "Hide Target Track". A big difference, in this case, is that OpenCPN has no record of the track. The tracking will start from the moment "Show Target Track" is clicked.

Hide anchored/moored targets, speed max (kn)
A target will not be displayed if the speed is less than the value set here. There are two exceptions to this rule, Aids to Navigation (Aton) and "Vessels Not Under Command". The rule is aimed at catching anchored or moored vessels. The "Navigational Staus" is set by the ships and may not be correct.
Be aware that the COG arrow will not be shown for any target with a COG less than this value, hence it's important to enter a very low value.

Show Area Notices(from AIS binary messages). More about AIS Area Messages here.

Show AIS targets real size. Zooming in on a target will eventually show a rectangle using the real size , if available. The picture below also shows how differences in course and heading are treated.

Show names with AIS targets at scale greater than 1:[select value]
With this box activated.....this is what you get!

Treat WPL sentences as APRS position reports.
APRS (Automatic Packet Reporting System) is utilized by HAM radio operators around the world.The NMEA WPL sentence is shorthand for for "waypoint location". If this box is ticked, a WPL sentence will be assumed to be an AIS-like APRS target.


Rollover: Tick the boxes for the kind of information shown when hovering with the cursor over a target. This is what you get with all the settings ticked.

CPA/TCPA Alerts and DSC/SART Emergencies: When an alert is triggered, a jagged circle in red is drawn around the target that set off the alarm. Additional events can be set here, drawing more attention to the alarm. For practical navigation, make sure your alarm sound is set.

Show CPA/TCPA Alert Dialog
Shows an alert dialog on the screen with target information when an alarm is triggered. This setting only applies to AIS CPA/TCPA alerts. A DSC/SART emergency will always generate a dialog.
Play Sound on CPA/TCPA Alert Dialog and DSC/SART emergencies
Sounds an alarm when an alarm is triggered.
Supress alerts for anchored /moored targets
Don't show alarms for anchored and moored targets.

Select Alert Sound. Select an alarm that suits you, instead of the installed default sound. This alarm will also be used if an anchor watch is set. Due to copyright issues, only a few sound files are included. The default location for these files are "/usr/share/opencpn/sounds/" on Linux and typically C:\Program Files\OpenCPN\sounds on Windows XP. Users can add their own generic ".wav" sound files. These files can be in any suitable place in the file-system.

Test Alert Sound. Test the selected sound and make sure this important feature is working

Enable Target Alert Acknowledge timeout. Once a target alert is acknowledged, wait the set number of minutes before the alert comes up again (if still applicable).

The Toolbox MMSI Tab

Read all about this tab here Setting Options

When exactly is an alarm activated?

An alert is set off if your boat is approaching the CPA, the blue dot on the extension of the course line, and the previously discussed set of conditions are met. Once the distance to the CPA increases, this happens when the involved vessels has passed each other, the alarm stops, even if the other conditions still apply.

+++

Types of Transponders recognized by OpenCPN
Class A
Class B
APRS Automatic Packet Reporting System Targets
ARPA Automatic Radar Plotting Aid Tagets
ATON Aid to Navigation, both "Virtual" and "Real".
BASE Base Station
DSC Digital Selective Calling Targets
GPSG_BUDDY GpsGate Buddy Targets
SAR Aircraft Aircraft participating in Search and Rescue.
SART Search and Rescue Transponder Targets

OpenCPN Remembers the Names of seen and fully identified target. The names are cached internally and helps Identify targets quicker on next start. Targets not yet fuly identified, were the name comes from the cache, are displayed lime green. See example below.
The AIS name caching can be turned off in the opencpn.ini/opencpn.config file by adding a line like this.
[Settings]
.....
EnableAISNameCache=0
.......

Quick Reference for targets:
Note that AIS targets reporting position unavailable will be rendered in grey colour.

An active AIS SART and is a distress call equal to a "Mayday" transmission.
More about AIS SART.

Icon displayed when testing an AIS-SART device.

Aircraft participating in Search and Rescue.

Potential Danger.

No Danger. Not Identified (Static voyage data not received)

No Danger. Not Identified (Name from cached data)

No Danger. Identified

Lost Target

Ship which has lost fix - position unavailable. Displayed at the last known position.

Vessel not under command.

Vessel restricted in ability to manoeuvre.

 Vessel constrained by draft.

  Vessel aground.

Vessel engaged in fishing.

High Speed- and Wing In Ground- crafts. This includes Hydrofoils, Hovercrafts and low flying crafts utilising the ground effect.

Anchored or moored. Displayed when the transmitted "Navigation status" is "at anchor" or "Moored". There is no guarantee that this status is correct, as it is set manually on the transmitting ship...

...illustrated by this ship. Note the black line on the yellow circle. This indicate that the vessel is turning to port (left), also illustrated by the lag in the display update. ROT - Rate Of Turn is available in the "Ais Target Query" dialog, through the right click menu.

The V-shape stern indicates a Class B target. Tugboats and pilot boats very often carry Class B transponders. These are often designed specifically for small commercial boats, fishing boats and pleasure crafts.

Targets is complying with the Euro AIS Inland specification.

This vessel has the "Inland Blue Flag" set, it's a part of the European, Inland AIS standard. The "Blue Flag" signal, commonly seen on inland waters, indicates that the vessel requests a "stbd-stbd" passage or crossing. This Blue Signal is manually switched on/off, by the target.

Aton, Aid to Navigation, for example a Lighthouse or a Buoy with an AIS transmitter.

Aton, Aid to Navigation, that is off it's suposed position. For example a buoy equiped with AIS that has come adrift.

Virtual Aton, Virtual Aid to Navigation, not a real marker. Can be useful for a range of situations. A new wreck, is one example. Further explanations.

Virtual Aton, off position. Actually seen in the wild, but may be a user config error.

AIS Base Station

The following tagets only displays if DSC messages, GpsGate mesages, Radar or APRS messages are mixed in to the incomming AIS stream, by using, for example a multiplexer. More on the following pages.

DSC Station. Only the DSC message received. The position contains only degrees and minutes of Latitude and Longitude.

DSC Station. DSC and DSE messages received. The DSE message contains the missing decimals of minutes of Latitude and Longitude. The result is a much more accurate position.

DSC Station transmitting a distress signal. Treat this as a "Mayday" call.

GpsGate Buddy target.

ARPA Target

APRS Target


Go to Table Of Contents

AIS SART

The US FCC has recently approved transmissions by AIS SART devices. These devices were originally designed for SOLAS class ships as an alternative to radar SARTs for carriage on life boats, but the efficiency of design has encouraged applications down to man-over-board devices. (www.exactearth.com/media-centre/exactblog,May 3, 2012)

Search And Rescue Transponders (SART) or PLB transmitting AIS messages are now available on the market. In an emergency situation the position will be displayed as an AIS target in OpenCPN. AIS SART can be a device on a vessel, in a life raft or a personal Man Over Board (MOB) device.

If you and your crew have personal locator beacons, transmitting AIS emergency messages, and the MMSI number of each device is entered in Options->Ships->MMSI Properties->New, OpenCPN from version 4.0, will automatically work as a man overboard tracking device.
Read more in Man Over Board .

The common thing is that the icon below marks an emergency.

SART icon, distress target display. This is a "Mayday".

On OpenCPN a distress signal sent by a SART, triggers an visual alert and a warning sound, if this is activated in the ToolBox-->AIS Tab.



Once the alert is "Acknowledged", the target behaves as any other AIS target. In the picture below the cursor is over the target. The SART target will persist on screen for 18 minutes after the last transmission irrespective of other settings for AIS.
SART alerts always have priority over DSC and CPA alerts.




And here is an AIS target query.



AIS SART messages and DSC distress calls are always found at the top of the AIS target list.



Testing
It is possible to test a SART, to make sure it works.



Icon displayed when testing an AIS-SART device.


Go to Table Of Contents

AIS Area Messages

To display the messages, tick the Options->Ships->AIS Targets->Show area notices(from AIS binary messages).

Many countries around the maritime world are testing the AIS binary messages. Expect a lot of development in this area.

In OpenCPN, this is very much a work in progress, the areas were only added April 2012 and the messages in December 2012.

Areas and the messages included for each area, are available.
In the US, Cape Cod is transmitting experimental Right Whale information. For testing, copy vislab-ccom.unh.edu/ais/notices.aivdm into a text file and point the VDR (Voyage Data Recording) plugin to this file.
These messages are updated quite often.



The area messages are found as the first entries in a normal object query for vectorcharts. The easiest way to display this dialog is to just double click in an area. The screen picture above shows that this works for RNC:s (raster charts) as well as ENC:s (vector charts). The first notice above is for the yellow tinted rectangular area while he second notice is for one of the circles outlined in green.

An overview of available massages compiled by IALA.
IALA has agreed to maintain a collection of regional applications for the AIS Application Specific Messages that are in use. The intent is to provide an overview to all interested parties of what currently exists.
The overview of available messages is available here.

Go to Table Of Contents

More About Target CPA

OpenCPN displays warnings about targets CPA & TCPA according to the setup in the AIS tab. But it's also possible to show CPA & TCPA for any target, that is no immediate danger, but where internal CPA calculation is still done, to assist in the decision making.

The AIS rollover window shows the CPA and TCPA of a target :



But it doesn't tell us where we and the target are at CPA, and if the target passes in front of us or behind us (i.e. should we speed up or slow down ?).

See the following (real) example:
We are sailing hard on the wind, while a vessel is approaching us, more or less from the wind direction. A CPA of 0.78 miles is normally safe, but there is this island in our way, meaning we had to tack towards the vessel, and it is still 14 minutes to go ...



What will happen with our CPA after the tack ?
Have we already passed each other or do we get closer when tacking just in front of the island ?
The answer to these questions is a context sensitive menu for AIS targets. Move the
mouse over the target, and when you see the CPA / TCPA info in the rollover window,



you can right click and select “Show AIS Target CPA”.



The function is only available when we have a “valid CPA”, i.e. when the rollover shows
CPA and TCPA (it uses the internal CPA calculation).

It simply shows the “CPA line” which is used in case of a CPA alert :



Showing the CPA-line as in the screen-shot above, makes life much easier. Nothing to worry about ...

At CPA ...
• we will be just in front of the island, exactly at our tacking position and
• she'll already be behind us (CPA line points backwards from our CPA position)
The CPA line is constantly updated, so you can follow the situation.

This is, what it looked like directly after our tack



To get rid of the CPA line for a specific target, right-click on the target and select “Hide AIS Target CPA”.



As already mentioned, the CPA line is shown only, when there is a valid CPA.
A minute later, we don't have a CPA anymore for the target --> the CPA line isn't drawn anymore !.



Another example :



He'll pass behind us, so “full steam ahead !”

Monitoring several targets
You can also monitor more than one target in parallel. Simply right-click on a second target and “Show AIS target CPA line”
Situation could be :
What happens to a second target if I get out of the way of the first one ?



Go to Table Of Contents

Radar Targets

3.3 Beta feature.
Some radars are able to create NMEA radar sentences from observed targets.
The ARPA targets, except for the way the data is acquired, are treated exactly as if they were AIS, including timeouts.





Arpa Target

Arpa Target

Arpa Target

Implementation details: https://github.com/nohal/OpenCPN/wiki/ARPA-targets-tracking-implementation
Discussion: http://www.cruisersforum.com/forums/f134/radar-nmea-messages-104048.html#post1239386

DSC and Buddy via AIS.

If DSC or GPSGate Buddy-messages are available in an incoming NMEA 0183 data stream, OpenCPN will show them with their own icons, and they will show in the "AIS Target list". They are not a part of AIS, but are displayed the same way, for convenience.

DSC is used on all new VHF set (or should be!). More on Wikipedia. To use this feature, check that your VHF set outputs NMEA 0183, in a way that can be connected to OpenCPN.

GPSGate is a commercial GPS tracking and sharing service. GPSGate Buddy Tracking is part of that service.

Make sure that Options--> AIS Targets -->"Play Sound on CPA/TCPA Alerts" box is ticked, otherwise the alarm sound (see below) will not be heard.

If OpenCPN receives a DSC Distress call, an alarm will be triggered, both visually and by sound.




A VHF/DSC distress call is treated in the same way as an AIS/SART call. Both should be treated as MAYDAY calls.

Quick Reference.


DSC Station. Only the DSC message received. The position contains only degrees and minutes of Latitude and Longitude.

DSC Station. DSC and DSE messages received. The DSE message contains the missing decimals of minutes of Latitude and Longitude. The result is a much more accurate position.

DSC Station transmitting a distress signal. This is a "Mayday".

GpsGate Buddy target.




A normal DSC target, is someone using a dsc-capable VHF



Distress message via DSC, Digital selective Calling, from an unidentified AIS target.



A green Buddy target on an island.



The AIS Target List View



Go to Table Of Contents

Extended Marks

The Route Manager and Gpx Data

• Through the Route & Manager OpenCPN can save and load waypoints, routes, tracks and layers using the GPX transfer format.
• This lets you save your routes and marks so you can have more than the active ones - for example to do route planning, or archive existing data.
• GPX format is supported by a wide variety of programs.

• You can have as many saved files as you wish, there are no limits on the number of saved files.
• Use this for passage planning by saving multiple possible routes for a passage.
• Save routes and tracks for historical/log purposes.
• Prepare layers as an aid to navigation en route.
• All Navigation Objects on this page, except for "Temporary Layers", are persistent between sessions. More here:Navigation Data Backup
• All objects visibility is toggled by clicking the "eye" , or other icon, to the left of the route/track/waypoint/layers name, on each line. A red X across the "eye" or icon (for marks) means that the object is invisible.
• All objects can be sorted by the header in the columns in the Manager. By clicking "Route Name below, the routes will be sorted alphabetically, pressing once again reverses the order. Similar for the column "To", the destination.
• Select multiple objects in the Routes, Tracks, or Waypoints tabs, individually by CTRL + leftclick, or in group by SHIFT + leftclick, for export or deletion.
• Double-clicking on a Waypoint, Route or Track brings up the respective Properties dialog.
  

  Routes

  
  
• Click the "eye" to the far left on the line with the route to toggle if the route is displayed or hidden on the chart. A small dialog let you choose, if existing marks, included in a route, will also become invisible. When a route is turned visible, all the shared waypoints are also made visible. Once a route is deleted, such a mark will go back to be a "normal" waypoint.
• To Sort routes click "Route Name" or "To"
• Properties:This button brings up a new dialog with settings that can be changed for each route.
• 
• Wpt 005 is right-clicked, and new dialog has popped up. The waypoint properties can be reached and edited. For example, change the default name, "005" in this case, to something more appropriate. Read more in the Extended Marks section. The waypoint can also be deleted. The last entry, "Copy all as text" copies all Route Properties for pasting into a text or Spreadsheet document.
• 
• Plan Speed The overall planned speed for the route. The speed for each leg can be set by going to the waypoint Properties->Description tab for the waypoint that starts the leg, and write in the speed. For example " VMG=9.7". [Unfortunately this approach presently excludes writing descriptions for the waypoint. One or the other, be warned!] The Plan Speed value is persistent and will be used for further routes, unless changed. The default value is 6.0 knots.
• Departure Time:With no departure time the ETE (Estimated Time En route) is calculated. Enter a Departure Time and the ETA will be calculated. Make sure to press "Enter/Return" after entering a departure time. This guarantees that the entered time is used in calculations.
  To enter the present time, enter ">" (meaning: "Now") in the departure time box. This works provided "Time shown as" -> Local@PC is selected. Press "Enter" and all the times in the "ETA" column will change. ">" differs from entering the same time manually, say "5/23/2011 08:00":
• - "5/23/2011 08:00" - calculates departure at 0800 on May 23rd 2011 from the first waypoint of the route
  - ">" - issued at 0800 on May 23rd 2011 - calculates departure Now from the current boat position, including the distance to the first waypoint of the route
• Times shown as: UTC is a new name for GMT. LMT is a local mean time based on the present longitude. For Local Zone Time one can also enter the keyword "now".
• Color: Set the displayed color of the track or keep the default.
• Style: Solid, dashes, dots, a combination or keep the default.
• Width: Set the width of the track or keep or keep the default.
• Marking a line with the leg number and the destination Waypoint in the Properties Dialog also marks the Waypoint on the chart with a blue square.
• The lower part of the Route properties dialog now has a Print Route button. It is possible to first select what features to print before being sent to the normal print routine.
• Extend Route:Extending is possible only when it is obvious, what should be joined with the current route (current = visible in the Dialog). Eligible are all visible route points shared with, or lying nearby to the current route's endpoint. If there is exactly 1 such point, then it is considered obvious, and the Extend button is enabled. If there are more, some should be hidden before proceeding, until just 1 remains.
  Routes are extended forward, based on the geographic location, next route point must be very near, as when mouse-extending the route. If the next route point is to far away for extending, just create the joining leg and extend twice.
• Split Route:For splitting, the split point is selected as the row in the listing. The point-of-split becomes part of both new routes (shared) or tracks (cloned). Original route/track is deleted.
• Here is a basic example of first splitting then extending. The test route is shown below
• "Split Test_A"
• In the Route Managers property dialog for the route we have selected a waypoint where we would like to split the route. The "Split Test" Route now consists of two parts, that has been renamed.
• 
• Next we extend the first leg "Split Test_A" with the second leg "Split Test_B". This extended route s now named "Split Test_B_plus.
• 
• Activate/Deactivate: Activates/Deactivates a route marked in the left part of the window.
• Zoom to: Zooms in on a route marked in the left part of the window.
• Reverse: Reverses a selected route. It's possble to cancel the reverse operation through a confirmation dialog.
• Delete: Deletes selected route or track. Use the Shift key to mark multiple routes for deletion. This also work in the other Route manager tabs.
• Export Route: Save the route on your computer for later use (import)
• Send to GPS. Send the Route to your GPS. Pressing the button activates a dialog were an output port is selected. This port does not have to be listed in "Connections" as it is an independent feature. This choice also appears in the right click menu for routes and waypoints. For Garmin Users, make sure that the ToolBox->GPS->"Use Garmin GRMN/GRMN(Host) mode for Waypoint and Route uploads" box is ticked. The reason for this is that Garmin units cannot accept route uploads via NMEA0183. This is a "design feature" of all Garmin receivers.
• 
• Delete All. Be careful. If you know you have saved the routes on your computer and are able to import the again, this is a simple way to clear the screen from routes. Better be safe than sorry, so save before deleting, if you want to be able to use the routes again.
• Import. Import one or more previously saved Routes, or Routes from other gpx compatible applications. It is possible to select and import multiple routes. The default waypoint icon bitmap is a circle. This kicks in if the icon in the imported gpx-file is not recognized.
• Export All, now called "Export All Visible..." Saves all visible routes, waypoints and layers, in one gpx file. This is done through a normal file saving dialog.
• If a Tidal Height Curve Dialog, for an individual tidal station is shown on the screen, the tidal situation for this station will be tabulated along all route points in the route properties dialog. It is essential to enter a departure time and a planned speed. Once "Enter" is pressed the tidal column will show the nearest High or Low water considering the ETA at each waypoint.
  
  
• If no tide dialog for any station is open and a waypoints name contains the string @~~<name>, for example "@~~York Spit Light", then the tide report for the closest station with matching name is shown in the tide column for this waypoint. The most appropriate tidal station for each waypoint can thus be selected.
• When entering a departure time the ETA, Expected Time of Arrival will be shown, instead of ETE, Expected Time En-route.
• The individual waypoints "Description" field can contain the setting of planned speed specific just to the next route leg (e.g. "VMG=4.5;") and/or the specification of Estimated Time of Departure from this waypoint (e.g. " ETD=2/14/2011 12:00;"), allowing for planning extended stopovers. Time can be specified as UT, LMT or local zone time at the PC (default).
  

Tracks

• Make sure that you have read all about Automatic Daily tracks and track Highlighting in the Documentation for the Toolbox Settings
• The visibility of tracks is controlled by clicking the "eye" on each line. Tracks can be sorted by clicking the column headers.
• Tracks are extended backward, based on the time-stamp sequence, a track is selected, which ends as the latest one before the start of current track. Tracks are extended as a single segment if they share the extending point. If they ha no common point a new "empty" segment, with no visible track, is added. Joining two tracks (i.e. extending a track) results in just track one remaining. It may look like two tracks but the Route Manager treats it as a single track.
• "Merge Selected Tracks" is an alternative to "Extend Track", where tracks are joined. The difference is that Merged tracks are visibly joined by straight track-lines. Read on for instructions on merging tracks.
• If you have ever hit the Track icon by mistake, or closed down OpenCPN in the middle of a passage, you know that it's very frustrating it is, to have a voyage split up in a number of different tracks that does not come together.
• This can be fixed. Just select any number of tracks in the Track tab of the Route Manager window, right click the mouse to bring up the context menu, and choose to Merge Selected Tracks. The selected tracks will be merged in chronological order, with the track properties (name, color etc) of the resulting track keeping those of the earliest track in the selection.

• "Copy as text" copies the track name, unless it's the default time stamp, and the track distance.

• The result of clicking the merge button.

Reduce Track Data

• Do you have have massive amounts of tracks and finds them bogging down OpenCPN? This feature is for you!
• It is available from the context menu in the Track Manager. Right click on an existing track, and then click "Reduce Data..." .

• Pick one of the options, it reduces the amount of points in an existing track while maintaining the specified maximum error between the original track and the reduced track. Testing on an old OpenCPN track or an imported track, with an error setting of 10 or 20 meters tracks, will, in many cases, reduce the size to less than half and one can't really see the difference.
• Tracks made with the new intelligent dynamic tracking available in OpenCPN will not reduce much, unless a large error is tolerated.

Track Properties

Waypoints

• Control the visibility of each waypoint by clicking the waypoint icon to the left on each line. Sort the waypoints by clicking the column headers.
• New. Create a new waypoint. This brings up the waypoints properties dialog. The default position is set to the current position of "Own Ship".
• Properties. All about the dialog in Extended Marks
• Zoom to centers the chart display on the waypoint.
• Go To. Makes an instant route from present position to the mark and activates the route. A similar instant route is created by right clicking and selecting "Go To Here" without first creating a mark. This instant route will be listed in the Route Tab.
• Export Wpt and Send to GPS buttons behaves similar to corresponding buttons for Routes.
• Delete All, does not delete any Man Over Board marks. All other marks are deleted.
• Use the Shift key to mark multiple waypoints for deletion. This also work in the other Route manager tabs.

Layers

• Layers are one or more routes, tracks or waypoints that have been saved together in a gpx file. A layer is represented as a single gpx file. A layer is persistent and protected from changes. A waypoint in a gpx file for example, can be imported either as a "waypoint" or as a layer. The difference is that when imported as a layer it cannot be changed or deleted.

The Route Managers Layer Tab

• Layers are useful for many things. It can for example be used to update charts with new navigation marks and dangers as per Notices to Mariners, and to add Radio Call-In Points or to build a database of lights and locations, that will be visible on chart regardless of current scale. See the first picture above, where French and UK forecast areas are good examples of Layers. In the second picture, a very good celestial fix, plotted with a gpx script has been saved as a layer.
• More advanced uses could for example be an interactive cruising guide, using the possibility to embed links in waypoint descriptions.

When is a feature a part of a Layer?

• Layers are immutable, nothing can be changed. This could make them confusing, unless you are aware of the fact that they are .... layers!
• To see if a waypoint, route or track, is a part of a layer, right-click the object. If it is part of a layer, the context sensitive menu will say so. Alternatively, open properties and check the top of the dialog, if part of a layer, the layers name is printed. As always,double clicking on a object, directly brings up the properties dialog,

  
  

  
  

• A route belonging to a layer is also identified as such, by just hovering with the cursor above the route.
  
• A Route belonging to a layer also has the option "Activate". It can thus be used, but still, no changes can be made. A much more flexible option, would be to import the route layer file as a normal gpx file.

Handling Layers.

• Layers can be created in OpenCPN, and saved as a gpx file, or be created offline, manually or by scripts, for example.
• Layers that are saved in a directory called "layers", in the same place that holds your opencpn.ini(config) file, are automatically loaded on start of OpenCPN. These layers will be listed in the Route Managers Layers Tab on start up. The first time they will all be visible. Adjust visibility by clicking on the "eye" in the first column. This setting will be remembered. Have a look at the first picture on this page!
• The easiest way to find this directory is to go to the - button in the ToolBar and look all the way down in the first tab (About).
  In Linux create the directory: /home/$USER/.opencpn/layers.
• On Mac OS X, the location is "/Users/"user name"/Library/Preferences/User Icons". Note that "library" is a hidden directory in "Lion".
• Any subdirectories in the layers directory, are also loaded.
• Layers worth keeping, could be kept in the mentioned "layers" directory and visibility during a session can be handled through "Hide from Chart" or "Show on Chart" buttons. New layers, gpx files, can easily be added in a subdirectory of it's own.
• A few restrictions apply to layer marks. A layer mark cannot be used to set anchor-watch on. If right-click-selecting co-located objects, priority is given to non-layer objects.

The Route Managers Layer Tab.

• Temporary layer: Any gpx file can be imported as a layer. This can be used for developing layers, or for import from a user defined directory with predefined layers, as necessary. Layers imported this way will be saved when closing down the computer, they are persistent. More permanent layers should be kept in the "layers" directory, as described above.
• Delete: Unloads the layer, but doesn't of course touch the originally imported gpx file. A progress bar will appear when deleting large layers. It is not possible to stop the deletion, once started. For size restrictions, see below.
• Hide from Chart or Show on Chart Controls if the marked layer is visible. The same thing can be achieved by clicking the "eye" to the left of the layers name. A red X across the eye marks a hidden layer. See picture above. These settings are persistent, they will be remembered after a restart.
• Hide WPT Names Shows a visible layer without waypoint names. This helps to un-clutter layers, when zoomed out.
• List contents or Delist Contents Listing is this context means showing the individual points in the layer as waypoints in the "Waypoints Tab"
• Import GPX.. and Export All.. Warning these buttons has nothing to do with Layers. They work as if you are in an other tab. For import use "Import New Layers". For export, create layers as described above.
• Export All Visible.. exports all visible layers, routes and waypoints to a gpx file. Use this button to create new layers, for example. Just save the gpxfile in the right place, described above. Note that "visible" in this context is the opposite to a layer, route or waypoint being "hidden". This means that objects not visible on the screen, may be included.
• A progress bar will appear when exporting large layers. It is not possible to stop the deletion, once started. For size restrictions, see below.
• If a layer includes extended marks, linked to pictures, for example, the pictures will not be exported, only the links to the pictures. To "export" the whole layer to another computer, copy all the pictures separately. Adjust all the links in the gpx file, to the new computer, by doing a "search and replace" in a text editor on the new computer.

Size Limits for the Layer feature.

• OpenCPN is not suited to handle very large permanent layer files. Exporting and deleting such layers bogs down the program. With older hardware or limited available memory, even these recommendations may be to optimistic.
• OpenCPN 4.0 has refined the track and layer logic to improve performance with large tracks. See next paragraph.
• Newly developed static layers by argus.survice.com shows that OpenCPN has problems with very large layers consisting of waypoints named after the depth at the position. With 10,000 + posistions it's necessary to consider some rules when using OpenCPN. If you disregard these rules, expect bad performance.
• Deactivating OpenGL may improve the performance somewhat.
• Always load the files as a temporary layer, zoomed in on your local area. Never load when zoomed out. Why? Zoomed out OpenCPN has to handle all wpts at the same time when zooming/panning. Zoomed in it just a handful of wpts at the same time.
• An alternative is to load a file when zoomed in on an other area. This goes quick. Then promptly make the layer invisible. Only make the layer visible when zoomed in on the actual area.
• Never zoom out with these files loaded, unless you make the layer invisible first. There is no point in this anyway as all you will see is a lot of black "smear".

More on creating layers and saving data.

• Have a look at Navigation Data Backup

Where to find ready made Layers?

• A few samples are available in Download->Layers Library on the OpenCPN.org.

Go to Table Of Contents

Great-circle Sailing

Very few cruising boats needs to use Great-circles, but it's certainly an important consideration for commercial vessels across the North Atlantic and North Pacific.
The advantage of a great circle is obvious, the shorter distance. The disadvantages, depending on latitude, could be quite a few. Colder weather, stronger winds, higher seas and perhaps even icebergs. The great circle is just one factor in the decision making, when planning a route, the weather is likely to be the deciding factor in most cases.

OpenCPN has a builtin Great-circle tool as well as a Great-circle plugin.

The built in Great-circle tool.
The "Measure" tool in the right-click menu and the "Create Route" button on the ToolBar switches seamlessly to a great circle mode when asked to do long distance tasks. This mainly happens when using these tools in some east-west direction and far away from the equator. The mode kicks in when the difference between the normal, rhumb line and the great circle becomes larger than two nautical miles. This will be some 0.2% to 0.5% of the total distance, depending on latitude and direction. When this happens a clear curve towards the pole will appear.


The Measure Tool



Testing the measure tool for Manila to San Francisco (approximately). For a good illustration to Great-circles, find a second point that is opposite the first, on the other side of the globe, and just move around slightly.



Once the first leg in measuring is done, it's plotted as a rhumb-line, to keep things simple. The active leg is still displayed as a Great-circle, if long enough. The distance displayed is the combined Great-circle distances.



The "Create Route" Tool



If you answer no to the above question, OpenCPN will use a traditional rhumb line for the leg. Answering yes, will kick the Great-circle option into action and a number of intermediary waypoint points will be created. There will be at least 3 waypoints. The exact number of waypoints is calculated by OpenCPN and is appropriate for most cases.



The created route is now available in the RouteManager dialog, as a normal route.



As a real example let us looka at a route from Mossel Baai South Africa, to the western entrance to Investigator Strait South Australia. The Rhumbline is 5660 mautilcal miles, and the Great-circle, as approximated by the created route is 5249 miles. The "real" Great-circle is som 15 miles shorter.



Composite Saling



Composite sailing is a Great-circle sailing with a maximum allowed latitude. OpenCPN has no such built option, but it's easy to create.
Above is the same route as before designed for composite sailing, not going further south than 45° S latitude. Start a route at Mossel Baai extend it until 45° S becomes a tangent to the visible Great-circle. End the route.



Do the same thing, starting with the destination and going backwards. Create a rhumbline route, using the two point along 45° S. The three routes together is the composite route. The total distance of the composite route is 5293 Nautical Miles.

Route Plugin

"Salty Paws" route plugin handles much more than Great circles, introduced here.



The plugin have a few features not present in the built-in tool. It can calculate a composite route, and the distance between the waypoints can be set by the user. The end result, however, is a "gpx" file that is exported, and then imported into OpenCPN via the Route Manager.



A Great-circle from Cook Strait to Cape Horn limited by 60° S

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Using Routes

To include existing waypoints in a route

How to use split and extend - an example.



Hm...a bit of a miss in the planning. An islet with a shallow bank extending southward on our route. We put two marks north of the obstruction and would like to include these in our route.



The waypoint west of the islet is #2. We mark this in "Route Properties", from the right-click menu. The Button "Split Route" is highlighted, meaning it is available to use. This is exactly what we want to do, so we click the button and split the route at wpt #2.




Right click at #2 and choose "Append Waypoint",



Move the cursor to the first triangle, and answer yes to "Use nearby waypoint?".
Then move the cursor to the second triangle , and answer yes to "Use nearby waypoint?".
Same thing for the original wpt to the east of the islet.



Click "Activate Route" to see that this extension worked.



Once again mark "Route Properties" in the right-click dialog. #3 is the last wpt in our "new" temporary route. The "Extend Route" button is highlighted, so we click it.




Open the Route Manager to view the result. Notice the naming of the routes. _B_plus is active. What remains is to delete route _B and to rename _B_plus to a suitable name, for example the name of your original route.



Deleting route _B.



And here is the finally adjusted route.

This was just an exercise.....in real life, it would be easier to just move the existing waypoints in the route, to avoid the Islet.

Go to Table Of Contents

Weather Routing

Users have the choice between using qtVlm or the Weather Routing Plugin. qtVlm is probably the more mature and stable choice and is described here.

OpenCPN can import optimized routes from the Free and OpenSource QtVlm program. Make yourself familiar with QtVlm if you intend to use it, as many things are done differently from OpenCPN.

QtVlm Documentation and Installation
QtVlm Thread on OpenCpn Cruiser's Forum
OpenCPN and QtVlm Summary of Route Transfer, see below


Before going any further, make sure you really understand grib files, what they are and their limitations. A good place to start is Franks Singletons pages.

Let's look at an example of importing an optimized route from QtVlm. It's a situation most of us try to avoid. Going across the Bay of Biscay with an active Atlantic Low just west of the British Isles.
The busy, time constrained, delivery skipper intend to find the best route from Lizard Point to Cape Finisterre. He has entered into QtVlm, the constraint, to route away from more than 30 kts headwinds. Below is the QtVlm optimized route based on the latest available grib file. Note that QtVlm doesn't know anything about tidal streams, currents local squalls nor about the state of the crew etc. These are more reasons why the final route always is the responsibility of the skipper.



Right-click on the route and export in the kml format.



Open OpenCPN. Right-click and "Paste Route"



This looks a bit ugly, and both the route and all waypoint have been exported.
We want somthing better!



One alternative is to let QtVlm (Edit Route) "Simplify" the route before copying.



Another alternative is to first use the "Paste Track" option.

*Note that this is no true track, it's just another way of exporting a route, possible due to the KML format. A track describes where we have been in the past, while routing is planning for the future. Importing the track gives a "light-weight" overview of the suggested route. Read more about the Grib Weather Plugin.



Next open OpenCPNs Route Manager Track Tab and press "Route from Track".




Much better. We now have a track with a route on top. Right-click and delete the track.
Next, it is smart to display the same gribfile, used by QtVlm, in OpenCPN, using the Grib Plugin.

All this looks impressive, but it's still based on a grib file. So it's still based on a computer prognosis, with no human input. All other reservations connected with gribs, still applies. An on board calibrated barometer is a good way to check what confidence can put on a grib forecast. Read more about the Grib Weather Plugin
A reasonable polar diagram is essential as well. Producing one is standard procedure on racing boats, but not that common on cruising boats. Cruising specific factors, such as "comfort" also plays a part in a cruisers true performance capabilities.

Summary of Route transfer process.

Using OpenCPN and qtVlm in "Real Boat Mode"
QtVlm English Documentation and Download is here .

Copy Routes

OpenCPN to QtVlm

• OpenCPN Right click on the route, pick "Copy as KML", Pick "KML with extended waypoint data (qtVlm)"
• QtVlm Right click on the Ocean, pick "Paste a Route" or Hit "CTRL-V"

QtVlm to OpenCPN

• QtVlm Right click on the route, pick "Copy Route xxx"
• OpenCPN Right click on the Ocean, pick "Paste Route"

Copy Tracks

OpenCPN to QtVlm

• OpenCPN Right click on the Track, pick "Copy as KML" Open Text Editor, Paste into new txt, save as .KML .
• QtVlm Pick "Routes- Imports Routes - In Ortho mode - browse to the directory, Pick the *.kml file.
• Note If all of the Track (now route) does not show up, current Grib data is not long enough.
• Note: Route Manager "Route from Track" selection, then simply copy the route.
• Note: Route Manager also provides Export Track as Gpx, however qtVlm does not support *.gpx format.

QtVlm to O

• QtVlm There are no tracks in qtVlm, just copy the route.

Using GPS in OpenCPN and qtVLM at the same time

Linux only:
Connect to your Gps using GPSD in OpenCPN.
Then issue this command:
$gpspipe -r | socat - PTY,link=/tmp/gpsout,raw
Now use "/tmp/gpsout" as the serial port name in QtVlm.


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Planning Data

The examples shown on this page are all suitable for import as layers, as that will prevent any waypoint from being moved by mistake.

Need to see some offshore weather observations?

NOAAs NDBC site gives access to a lot of offshore observations from buoys and ships worldwide.
To easy visualize all this data the "ShipWxRep" script transform a limited set of all the available data into gpx waypoints. The format, as seen above is "wind direction, wind speed, time for observation, and air pressure". This can be helpful when evaluating the accuracy of grib files, even though the best tool in this respect probably is a calibrated digital barometer.

Plotting Miami Tropical Forecast Advisories.

If you only have access to low bandwidth Internet, this script is a way to quickly plot the contents of, for example an email, containing the forecast advisory. In any case, it is a good idea to have the forecast track of a tropical system available where you normally do your navigation and planning.



Download the gpx scripts here. The old great-circle script is included. For some help run each script without arguments.

Go to Table Of Contents

Navigation Data Backup

Saving sessions

• The navobj.xml.[1..x] takes care of your session data backup. This means that when you start OpenCPN it "remembers" the state of your last session.
• A rotating backup of navobejcts is automatically created on every program run. OpenCPN keeps backups of the last 5 runs. This can be changed.
• In the opencpn.ini/opencpn.config file you can find a configuration setting to control the number of backups kept, defaulting to KeepNavobjBackups=5. This value can be changed using a text editor.
• The backups are then stored in files navobj.xml.[1..x] (in the same directory as the ini file) where .1 is always the newest backup and the oldest is removed on the next program run. The file that will be loaded on next start is called navobj.xml.
• The backups are only rotated if the navobj.xml file has changed since the last backup was created. This prevents overwriting good backups with a broken version, more than once.
• Note that the navobj.xml files reside in a folder that is hidden by default by Windows. More information is available here.
• To load an old backup, exit the program. Find the backup you want to use. Rename it navobj.xml. Start OpenCPN!
• The navobj.xml.[1..x] files are gpx files and it is also possible to directly import them back into OpenCPN. Press the "Import GPX" button in the Route Manager.

• Navobjects are not lost during a normal upgrade to a newer version.

• You have useful automatic rolling backups of navobj.xml, as described above.
• Copy them somewhere safe before you run OpenCPN again, as they are automatically rolled over, and you lose the oldest one for each invocation of OpenCPN.
• Rename the "best" one as navobj.xml, and the contents will be automatically used by OCPN.
• The OpenCPN logfile also serves as a backup through the "LOGBOOK:" entries.
• These can be used to reconstruct a GPX track. A windows utility for hat purpose ia available here: https://github.com/nohal/LogBookExtractor/downloads

Saving waypoints, routes, tracks and layers for future use.

• For a more permanent backup solution, to keep routes, waypoints and tracks etc, that you may need in the future, consider saving the data by using The Route Manager and Gpx Data or use Layers
• Be organized. Create a dedicated directory, for example GPX_Routes, to save files worth keeping. Be careful to name all files in a manner so the content is obvious, without having to import the file into OpenCPN.
• Each tab in the Route Manager (except the Layer Tab) has a button "Export......". Use this to export one Waypoint, one Route or one Track at a time. Multiple selection is not possible in this version OpenCPN but will be implemented in the next version.
• Create a layer, a collection of waypoints, routes and tracks by making the features to be included in the layer visible. Everything else should be deleted or hidden. Every object that is visible on the screen when maximum zoomed out, will be included, not just what is visible on the screen for the moment. When you are ready, use the "Export all visible" button to create the layer gpx file.
• To Change an existing Layer, start with creating a backup of the existing gpx file, containing the layer, by copying it to a safe place. Make sure that no navigational objects are visible, that you don't want in the new version of the layer. Then use the Route Managers "Import GPX.." and load the layer to be edited. Do your changes to the layer and press "Export All Visible...", and save. If you made a backup, just overwrite the original file. Otherwise give the changed Layer a new name.
• Use your saved files by importing them back into OpenCPN. Press the "Import GPX" button in the Route Manager. Layers can be set up to load autmatically on starting OpenCPN. Read more in Layers

Night Navigation

Dimming the whole screen for Nighttime Navigation.

Change Color Scheme

Anchor Watch

• The Anchor Watch only works with an active gps. If the gps signal is lost, the alarm will be set off.

Go to Table Of Contents

Automatic Anchor Mark

CM93 Offsets

• Go to single chart (i.e. non-quilted) mode, with cm93 charts displayed. Use F9 to flip quilting on and off
• Zoom/Pan to the region of interest.
• Right click and activate "CM93 Offset Dialog"

• In the list of cells/MCOVR IDs, selected the one MCOVR of interest. The coverage area for this MCOVR object will be outlined with a heavy yellow border.



• Some cells have built in corrections already applied. The values wgsox and wgsoy, are offsets to bring the original chart cell to WGS84. See the first and third cell in the picture above. The values are for information only, and cannot be changed. These corrections are generally correct, but not always. Sometimes the corrections are wrong and sometimes there are no corrections where there ought to be. This is where this manual offset feature comes in handy.

• Use the spin controls on the right side of the dialog to adjust the desired user offsets. It is also possible to write numbers directly. Notice that positive corrections is towards North and East.
• In some cases it is not clear exactly which M_COVR ID that represents your position. A simple test will reveal if a mark reacts to (large) corrections.
• The offsets are automatically saved in the binary MCOVR cache files found in the program data directory as CM93/...

The Command Line

The Configuration File

About Plugins

OpenCPN has two default plugins pre-installed:

• Grib Weather Plugin
• Dashboard Plugin

Download Plugins

Plugin Versions

Blacklisted Plugins

Installing a Plugin

Enabling a Plugin

Problems with Plugins

Dashboard Plugin

The Dashboard Tab