OK, I've had a few days of tinkering with my setup, and I managed to make everything work! Very happy with it.
There were two obstacles I had to overcome: my own limited understanding, and the fact that the Nasa Clipper GPS
repeater is very picky regarding what data it gets.
As mentioned, I first had OpenCPN
send RMB and
RMC to an UDP port and in SignalK I forwarded this to the serial
port that connects the repeater to the RPi. This worked fine, even though I now understand it's not really supposed to.
In the new setup, I use SignalK's SignalK-to-Nmea0183 plugin
to generate RMC. This had the unexpected positive effect that the repeater started showing SOG and COG without having an active waypoint in OpenCPN
. Previously, I would have to activate a waypoint to see COG/SOG.
Then, I setup AvNav to output RMB to a UDP port and forwarded this in SignalK to the serial
port. Now, the repeater intermittently showed waypoint data, alternated by "No GPS
Dest". This behaviour I recognized, and it is due to the Nasa Clipper's peculiarities.
Now comes the really good part: In AvNav, I could specify the interval with which to output RMB. Default is 1 second. 0.5 seconds reduced the intermittent showing drastically, and with 0.4s the problem was gone!
So, time to look further. I already purchased the Ocharts-maps for my region, so I edited Avnav_server.xml to point to the chart folder, and... done!
It would be even nicer if this could be done in the GUI, but anyway, it's great that I could use the charts that I already had!
A question about the O-charts map: I was fiddling with the text/sounding text sizes. The settings page says that after a change in these settings, the cache will be emptied, but that doesn't actually seem to happen: the parts
of the chart that I already had looked at, kept the text size setting from before, while newly rendered bits of chart had the new settings applied. Is there a way to manually empty the cache?
Also, the missing icons bug was fixed, very quickly!
So, very happy user here! Now going to try it out in practice.