Solved. Intermittent COG on RP4 from Furuno GT-32

[Roda25]

My very first post. First a big thanks to Sailoog and everyone helping out in the community and posting here.
Thanks to you all I installed OpenCPN on a RP4 and got everything working more or less working by reading the manual and posts here.
I am a newbie to RP and linux, so this has been fun.
I have one thing though that I can't figure out and that I very kindly ask for your thoughts about.
I have installed the RP on our small old sailing boat that already had a Furuno GP-32 installed - and wired the GP-32 to the RP via a serial to usb adapter


Then I created a connection in opencpn and voila, I have SOG, position, but only an intermittent COG. Most of the time COG is blank, but then appears now and then.
This is my connection setup in opencpn, as you can see the only thing missing is the COG


Any thoughts greatly appreciated.
Thanks again

[Roda25]

I seem to have solved the issue - although I am not quite sure why.

Firstly, when I posted the above post, all the testing I had done was while the boat was docked in the harbour - so not moving (much).

I deleted the connection to the Furuno in OpenCPN and instead created the connection in Signal K, as I had read that I can filter out some of the NMEA sentences that I don't need in Signal K. I then created a new connection in OpenCPN to Signal K using Localhost as the address. That worked - and now my OpenCPN dashboard showed both course and speed the whole time - instead of an intermittent course before. It looked like it was now updating every 20 to 30 seconds, while the boat was moored.

I read somewhere last night that COG may not show correctly when stationary, so instead of trying to filter some of the NMEA sentences in Signal K, we took the boat out for a spin today - and the COG behaved perfectly - updating the whole time and with no missed data or dropouts.

So whether it now works because we simply went sailing - or whether it works because Signal K handles the NMEA data differently, I don't know.
But my problem is solved.
Thanks to everyone to took the time to read this - keep up the good work.

[sebba]

COG need movement. COG is based on latest GPS positions. If stationary, no COG. So what you have there is perfectly normal.

[Roda25]

Makes sense now - thanks Sebba