[TG] [TG11] 6001 holds then goes off course

[Jjb6161]

When I engage auto to hold course it works for 10 minutes or longer and then goes off course and I can’t get it to hold in auto usually for the rest of trip. Sometimes it’ll say no data but most often just shows the course I was on but goes off course

[Tom - Raymarine - Moderator]

Hello Jjb6161,

That sounds like you may have a problem with your fluxgate compass. They have a number of very fine wire windings and are prone to brittle fractures and intermittent end-to-end contacts in these windings after years of knocks and movement in their internal gimble. A No Data alarm when going into Auto mode is how the older pilots used to indicate a detected compass problem, and the other times when you don't get an alarm are probably when the pilot doesn't see anything wrong but is measuring a static heading value through the fluxgate, and hence doesn't know it's off-course.

The classic symptom of a broken winding in a fluxgate is a 'dead sector' in heading, where the pilot's compass heading doesn't change. There are fluxgate compass resistance checks that can be made, but in the first instance I would suggest just waiting until the problem occurs and then checking the pilot's heading by putting the pilot into Standby and then watching its indicated heading data whilst you do slow circles. Fluxgate problems typically show as a quadrant where heading does not update (or, if your pilot has a rate-gyro as well that damps the heading data, heading that drifts slowly or counts backwards.)

Regards,
Tom