A consistant 25 degree corse change may not be related to the AB, but to the power consumption
I installed a Raymarine Auto pilot on my last boat and the fluxgate compass
was mounted near the main battery cables
. The Autopilot
worked fine when I had fully charged batteries, but when the batteries were low and the alternator
was doing its 85 amps... It would throw the Fluxgate
The problem was solved when the installer move the compass away from the electromagnetic field....
I would check the Fluxgate compass location for any near-by power wires, especially the large main cables