Autopilot lesson learned

Had a baffling issue with a new Garmin autopilot during my recent shakedown cruise. Everything would be going along great using the autopilot when there would be a sudden sharp veer, left or right. This would happen randomly, sometimes minutes apart, sometimes days.

Hydraulic steering had no obvious problems. I had installed the main ‘brain box’, containing the electronic compass and gyros, according to Garmin’s instructions - low down, centered, slightly forward of center of rotation, away from any large motors, electrical cables, or other electrical equipment. The best place was on the deck beneath the galley, where I could access it readily by pulling a drawer out.

By chance I noticed that every time any of the drawers over the unit were opened, that initiated the veer. My initial thought was that it was the motion of the nearby pots and pans causing the issue, but it persists even when the drawers are empty. I now believe it’s the steel drawer runners. I suspect that they have some small magnets incorporated into them somewhere - the investigation continues. I’m guessing that Garmin never conceived of this possibility when writing their instructions.

Aside from that I love the autopilot and Garmin has been strong with technical support.

 

I had that problem because of my phone. The magnet in the speaker would make the steering go crazy when I sat next to it.

 

Suspicions confirmed. The drawer runners incorporate a small magnet. Relocation of the unit is on today’s project list.