GPS and Compass show different headings
I know this is a beginner question, but here goes. On my new (to me) boat, the compass and GPS show fairly different headings. I have a Raymarine C-60 and a Richie compass. I would assume that the GPS is the correct heading and that the compass needs calibration, but how do I know for sure?
Odyssey, '79 CSY 44 Cutter
Channel Islands, CA
"There is no unhappiness like the misery of sighting land (and work) again after a cheerful, careless voyage."