Autopilot Gone Crazy

[rpmerrill]

The BAY RANGER was back in the water today. I took a short shakedown cruise with a neighbor as a second mate. On the run, I actuated the autopilot on an old route that I used every time I took the boat "down the river". It went cockeyed, trying to hit the course but heading off in the wrong direction by about 30 degrees. It was very strange!

The neighbor said something about recalibrating the flux-gate compass by doing some circles. I decided I had better red up on this AND I didn't remember ever reading about this in the Garmin manual. (Recently re-read this winter.) SO, in the peace and quiet of home I found nothing.

Then a revelation... during my dinette seat cushion remove, recover and replace, I had to drop the flux gate and bracket last fall.

Back in the car, I got to the boat and fired up the systems. Sure enough the GPS compass did not agree with the (old fashioned) compass by ~30 degrees! While watching the display, I reached into the cave and slowly turned the flux-gate by hand until the compasses agreed. (Everything is operating on "magnetic" at the moment.

No time for a river run this afternoon but I'd say the problem is solved.
Has anyone else experienced this before?
Did I solve it?

 

[scross]

Probably!
When out autopilot went on the brink at the start of last season, Garmin told us to check the connections to the compass. Well, the darn compass bracket cracked while checking the connections. As a temporary fix, I taped the compass in place waiting for a new bracket. Fortunately, the compass brackets are cheap and readily available.
After the intermittent wiring fault (loose fuse holder) was finally identified and fixed by Garmin staff, we were off by as much as 120 degrees from compass autopilot heading to actual gps heading. After carefully rotating the compass while underway and checking the compass reading in all directions we are now within 1 degree to 3 degrees in agreement with independent gps bearings. And that is probably as good as I can get it!