Semi-automatic digital logbook for Signal K

[skybolt]

Just installed this a few months ago and it worked on my first test, had a few points and could see speed etc. But since then it doesn't log anything and shows no speed and zero points in between start and stop main point(s). 

I believe my issue if the SOG sensor, it is a paddle wheel that gets clogged frequently and doesn't register speed correctly and frequently displays 0 knts. Is there any way to select a different sensor like the a GPS for the SOG parameter in the logbook?

Thanks