Raymarine autopilot course data?

[Neil]

I have had some issues with the Raymarine Autopilot due to the fluxgate compass. The most recent one was due to a local magnetic anomaly, causing a large drift. Nothing can be done about that one other checking the charts and being aware of the issue.

When I first purchased the boat it had been out of the water for 2 years. The autopilot tended to lose the plot completely initially until I had used it for about 2 weeks. The problem was linked to the signal from the fluxgate. It could have been due to it being a bit damp, but I can't be sure, and it did settle down after the electronics had been used for a while and I had a dehumidifier on the boat to dry everything out. The autopilot seems to be driven by the fluxgate compass and not the GPS informed COG heading, with some kind of alarm from the chart plotter if the difference is too great. Can anyone confirm if this is the case?

[dawntreader]

As you haven't specified the model this is a 'generalisation'. The autopilot will follow the course determined by the fluxgate compass and doesn't 'consider' COG. This can be demonstrated by putting random metallic objects in the magnetic field of the compass and watching your boat steer somewhere unexpected  The alarm sounds if the autopilot cannot follow, or goes too far away from, the course ordered.
As a 'standard' start-up procedure, I always check for co-ordination of both helm compass and the read-out on the autopilot instrument. Bear in mind that local anomalies may cause these to differ slightly so always check again once you are out of port and underway.

[Craig]

Have you checked the physical location of your fluxgate compass.

I almost had a collision when my wife moved her Bras ( wire in the Bras) in the locker in our forward cabin where the fluxgate compass is located. Boat turned 70 degrees.

A friend had problems until he realised that his fluxgate was in a rear cabin but near the galley bulkhead. A metal plate was flopping around in the galley causing variations in the field sufficient to make the boat wobble about 10 degrees.

Craig
"Shirley Valentine"
Gold Coast
Australia

[Kibo]

From bitter experience I can advise looking closely at objects close to your fluxgate and as stated before don't forget about the other side of the bulkhead.... Two situations on different boats. 1. Spinnaker bags with metal rings to hold the tops open stored near the fluxgate. 2. First mate stowing cans of food on the other side of the bulkhead to the fluxgate....