st4000 Wheel pilot wont hold course

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Laundryman

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Just fitted a new fluxgate compass hoping that would solve the problem. Calibrated as per instructions. 6% deviation corrected as per instructions. Held steady course and corrected the Autopilot heading to match the compass. Switched on the autopilot to maintain present course. Wheel responds for a minute or so then veers off wildly 90 plus degrees. Any ideas why or advice please? Thanks Alan
 
I had symptoms like that once when my dad stowed a load of beer in steel tins right next to the compass. To be fair to him, the compass is mounted in a stupid place (moving it is on the list, but some way down).

Presumably, though, if you've just been working on the compass you will be mindful of its location and won't have surrounded it with ferrous objects.

So I dunno.

Do you have anything that can read out what your compass thinks the heading is? If that suddenly starts changing without the boat moving, then the pilot's reaction is reasonable but the compass has a problem. If the compass heading remains correct, then you need to look at other inputs to the pilot (rudder position sensor?) or the pilot brain itself.

Pete
 
I had exactly the same issue years ago and it was entirely baffling! I had various people look at it to find the problem, rudder reference, compass etc etc nobody managed to pinpoint it but consensus of opinion seemed to lean towards a slightly erratic power supply, seemingly very sensitive to even small fluctuations.

Sorry to not be more specific but it might be something to check, I never got to the bottom of it because I sold the boat.
 
Laundryman said:
Just fitted a new fluxgate compass hoping that would solve the problem. Calibrated as per instructions. 6% deviation corrected as per instructions. Held steady course and corrected the Autopilot heading to match the compass. Switched on the autopilot to maintain present course. Wheel responds for a minute or so then veers off wildly 90 plus degrees. Any ideas why or advice please? Thanks Alan
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Are your rudder reference wires crossed? If so you go straight until input is needed then suddenly winds hard over. Had that happen last year after I reconnected everything (wires crossed) after altering instrument locations. However I have also had two new control heads in 9 years, one of which was producing this fault, the other just went dead. One failed under warranty, the other I had to pay for.
 
If the fault is with the rudder ref then it is probably possible to repair it.
See my post #10 on this thread http://www.ybw.com/forums/showthrea...ition-sensor&p=4571338&highlight=#post4571338
All will be clear once you have opened it up. It's ok to cut and rejoin the wires to the unit in order to remove it.
The a/p display should be set to show rudder position. Port wheel the dots move to port, no dots amidships. Apologies if that is very obvious.
 
Have you reset to factory settings then gone through the calibration cylcle?

Also worth unscrewing the fluxgate compass and turning it by hand whilst watching the heading on the standby display to see if there is any point where the heading seems to stick or move wildly as the compass turns.

Another oddity is if the steering wires or connections have been fitted in a reverse way for some good mechanical reason - if so then there will be a software setting to reverse the wheelpilot movement. Unlikely I think.

if you've done that and checked all the wires then there may be an unfixable issue with the electronics. After trying everything else we fitted a new expensive course computer (as its called on our model) and the calibration worked immediately.
 
RupertW said:
Another oddity is if the steering wires or connections have been fitted in a reverse way for some good mechanical reason - if so then there will be a software setting to reverse the wheelpilot movement. Unlikely I think.
Click to expand...

Not sure for this specific model, but the commissioning instructions for S1 with linear drive say to connect the wires at random and then change them over if the rudder goes the wrong way. They don't even bother to explain which way is "right" first time.

Unlikely to be this problem if the OP's setup used to work and has not been interfered with, though.

Pete
 
jwilson said:
Are your rudder reference wires crossed? If so you go straight until input is needed then suddenly winds hard over. Had that happen last year after I reconnected everything (wires crossed) after altering instrument locations. However I have also had two new control heads in 9 years, one of which was producing this fault, the other just went dead. One failed under warranty, the other I had to pay for.
Click to expand...

Same with me !! wires crossed, It seemed to hold direction for a minute possibly because it was exactly 180 degrees out. Otherwise does yours go off and then hold ( on the wrong!!) course?
 
The symptoms are very similar to what happened to us a couple of years back. I fitted a new compass after the old one died and all worked fine for a period, then exactly what you described started happening, or at least I think it's the same. In our case, the control display would suddenly decide to pick its own heading to display and the autopilot would attempt to bring the boat on to the correct course to match the new random bearing. I did all the stuff about clearing metal away from the compass and checked everything I could think of. I was about to order a new compass when I got SWMBO to move the connecting wires and that caused the fault to repeat itself. I redid all the connections to the compass and that solved the problem. From this,I'd recheck the compass wire connections to ensure that they are good and see if that solves the problem. Good luck.
 
Bit of a wild card really, but just check that the belt is working correctly, ie it is not sticking in the casing, just in case it is a mechanical and not electronic issue.
 
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