Raymarine autopilot misbehaving

[lpdsn]

Under sail are you trying to get it to sail to the wind or to a compass course?

PS Apologies if that's somewhere back in the depths of the old thread.

 

[alisdair4]

Under sail are you trying to get it to sail to the wind or to a compass course?

PS Apologies if that's somewhere back in the depths of the old thread.

No worries! The autopilot is not yet set up to use Vane mode-so it was on a compass course.

 

[Bru]

The fluxgate is potentially too close to the engine*. It could well be that the magnetic field from the engine alternator (or even just the effect of big lumps of metal moving at high speed!) is interfering with the fluxgate

* two feet definitely too close, three would be borderline, the further away the better

If that's not the problem, see if you can find someone with a portable or pocket oscilloscope (I use a nifty little LCD screen job) and check for noise on the +ve supply terminal of the course computer when the engine is running (had all sorts of problems with a Raymarine X5 autopilot a while back which turned out to be caused by a faulty alternator)

 

[lpdsn]

Is there anyway you can record the NMEA/Seatalk messages? It still sounds like either the compass or rudder ref arm is giving out faulty data when the engine is running.

Strange that motor sailing works.

 

[prv]

Is there anyway you can record the NMEA/Seatalk messages? It still sounds like either the compass or rudder ref arm is giving out faulty data when the engine is running.

Both items emit simple analogue signals (the rudder sensor is just a variable resistor in a plastic pot), not NMEA or Seatalk.

(Agree the engine is obviously interfering with either the compass itself or its wiring.)

Pete

 

[alisdair4]

Have checked to see if the engine running affects a magnetic compass- no discernible difference with the compass held in the are of the fluxgate. Next step is to try moving the fluxgate.

 

[RupertW]

One way to check if the fluxgate is reading wrongly with engine on is to put autopilot on standby and slowly circle whilst watching the heading on the autopilot display panel. If it roughly follows the real compass heading and doesn't stick or even reverse as you go round then it's probably not the problem

 

[Slipstream 34]

Loose wiring..? Only apparent when vibration from the engine is present.

 

[sailorman]

Have checked to see if the engine running affects a magnetic compass- no discernible difference with the compass held in the are of the fluxgate. Next step is to try moving the fluxgate.

keep the compass low as well, mine is under the hanging locker sole forrard of the lead keel

 

[alisdair4]

Loose wiring..? Only apparent when vibration from the engine is present.

Could be, Slipstream. That would account for the autopilot behaving with engine running on tickover (ie when sailing). I have a whole weekend coming up to try all these theories out..!

 

[Simon054]

Before you think about buying a new control head check the cables, they are not normally tinned and corrosion can cause the issues you are having, I read about it on another forum having had a similar issue. My problem was moisture on the back of the unit around the sea talk cable but other people have had the same issue and it was the cables not allowing the signal through and giving spurious faults.