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AP not holding heading

Mar 24, 2012
Hunter 34 531 East Patchogue NY
Hoping to find help with my AP. My issue is that when I hit heading hold on my Vulcan 7 my AP (NAC2 controller) turns to port instead of holding course. Outbound last Saturday it only happened a couple of times but otherwise worked as it should. On my return trip Sunday it would not work properly. This happened on rare occasions last year as well so I recalibrated the AP and it seemed to work properly afterwards. A thread I had viewed asked about the addition of new items. I have added an electric windlass and a Fusion stereo and also have a handheld VHF at the helm that I never had before. I have a P9 compass which is set to auto calibrate. It is located in the V - Berth well away from the helm. I have a rudder position sensor and recalibrated that at the start of the season.
The compass is securely mounted as it has always been. Any suggestions?
May 17, 2004
Beneteau Oceanis 37 LE Havre de Grace
What setting do you have the autopilot on when it starts to wander (heading hold, nav to waypoint, wind hold, etc)? What do the electronic compass read outs look like when it’s wandering? If you set the autopilot to just hold a rudder angle (I think that’s called follow up mode) does it still wander?


Jun 1, 2004
Catalina 27 Mission Bay, San Diego
Besides calibrating, you might look through the configuration data to make sure the controller is using the desired compass instead of the Vulcan's internal gps. On my setup, which uses a tiller pilot, the device will default to the tiller pilots internal compass unless unless I set it to use the Vulcan's gps. There have been two occasions where I've had to go in the display and reset the configuration. I thought switching between course and wind mode was the culprit but haven't had any issues for the past two years.
Mar 24, 2012
Hunter 34 531 East Patchogue NY
Thank you for the replies! I went out today and the AP worked perfectly. I did check that the compass setting was correct. The only difference between today and last week was I was motoring today and sailing last week. I’ll be doing some more experimentation next time out.
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