Signal K charts, offline & online

In Signal K(SK) there are 2 applications, in SK appstore, that can handle charts

• Freeboard SK(FSK)
• Tuktuk Chart Plotter(TT)

FSK, preinstalled, uses the OpenSeaMap charts(OSC) when you are online. If you want to use offline charts or other chart resources you have to install "@signalk/charts-plugin"(CP)

Chart app

Installing

The install is done via SK appstore. Please note that the installation can take a long time since there are no binaries available. (Using a RPi 3B+ with SD card it took almost 10 minutes). Check the server log! Tested and works with Node.js V16, V18.

Settings

Go to settings for the CP, "Server => Plugin Config => Signal K Charts", and click on "Enable" "YES" and then "Submit". With user "pi" this will create the default directory, "/home/pi/.signalk/charts", for chart file storage.

Getting offline charts

If you are using the sample files, which are included in the SK install, and want an offline chart for that area please issue the following commands in a terminal/ssh session

cd /home/pi/.signalk/charts

and then download, 1.4 Gb, from the OpenSeaMap FTP site

wget https://ftp.gwdg.de/pub/misc/openstreetmap/openseamap/charts/mbtiles/OSM-OpenCPN2-Baltic.mbtiles

Then got to the settings for CP and klick on "Submit" which will update the meta data. This can be checked with

http://raspberrypi:3000/signalk/v1/api/resources/charts/

Viewing charts
Open the FSK app and select the charts according to the initial picture

Using online charts

As said FSK, by default, uses OSC online maps but it could be other online resources and here is an example, Eniro, which also will match the sample files.