calibration

Has anyone used their GPS set for magnetic North, to calibrate their bulkhead magnetic compass????? Seems to me one could tweek it more... any opinions welcomed...

Hi, I had a thought. My autopilot is a Raymarine S1 wheel pilot. Tomorrow I am planning to tune it up a bit. It's not really performing as well as I would like it to. There are probably something like 5 to 10 autopilots tops that people use on Ericsons. My thought is that it might be nice...

How closely should the mechanical compass, hand bearing compass, autohelm electronic compass, and handheld GPS "compass" agree on a boat? Mine do not agree exactly and I'd like to find out what is reasonable. Should one of them be considered the "reference" compass against which the others can...