Raymarine autopilot misbehaving

alisdair4

alisdair4

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midnightdrifter.net
Our new boat is a LM 32, with wheel steering and a Raymarine ST 6002 autopilot. We are just getting to grips with all the new systems - rather different from a Rival 32! When sailing, the autopilot works fine. When motoring, the autopilot doesn't seem to be able to cope - altering course by 30-40 degrees (always to Stbd) , then going into "off-course" mode.

Our previous experience is with a tiller pilot - also a Raymarine - which doesn't do this sort of thing!

Any ideas? I haven't re-calibrated the system, because the boat is so new to us.
 
Is that the one with the Type 1 drive? Have you tried disconnecting the drive to check it moves freely.

Other idea is to check the wiring to the unit. Is it underspec'd with too much voltage drop.
 
lpdsn said:
Is that the one with the Type 1 drive? Have you tried disconnecting the drive to check it moves freely.

Other idea is to check the wiring to the unit. Is it underspec'd with too much voltage drop.
Click to expand...

Not tried either - I get a feeling from the quality of the other work that the previous owner (now sadly no longer around) had done that they would not have skimped - but, worth a try.
 
A Raymarine agent in Plymouth gave me the following very usefull " hands on " diagnostic tip.

1. Engage the autopilot. If the wheel locks, the electric clutch is working.

2. Now give the display a large course alteration-+10, +10, +10, 30 degrees in all. If the wheel moves in the direction you asked it to and you hear the motor go " whirr, whirr, whirr " all is good. If not, read below.

3. Now repeat the other direction. If the motor does not whirr and the wheel move, give the side of the wheel a slap downwards in the direction you expect it to move. If you now get wheel movement and the whirr of the motor, remove the motor and inspect the little carbon brushes and the commutator. You will probably find they are stuck and covered in carbon dust from the brushes.

On our previous boat I found the brush holders had no slot to allow the brush springs to keep pushing the brushes into contact with the commutator. Bending the end of the spring at right angles allowed continuous pressure. The brushes were only about 15% worn but were stuck and the commutator was filthy.

It is still working five years later.

Worth a try........................
 
I don't know if it's relevant to your model but: For the first few months we had our boat the autohelm did all sorts of silly things, until we realised/discovered that the clamp connecting the ram to the top pf the rudder stock was loose and couldn't be tightened sufficiently to grip it tightly anyway; we fitted some shims around the rudder-top and nyloc nuts to the clamp bolts, it's been spot on ever since.
 
The erratic nature of the error added to the fact that it only happens under motor suggests that there's a loose connection somewhere in the system that is being vibrated loose by the motor. I'd check all the connections in the autopilot system paying particular attention to the connections between the flux gate compass and the course computer.
 
Kwik Decision said:
Given that when sailing the op reports that the autopilot works fine I would say it is more likely to be interference from the engine / alternator. Any other problem would probably be present when motoring or sailing.
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That sounds likely to me. Normally the autopilot has its easiest time when tootling along under engine so if it only goes wrong then it sounds like some kind of voltage problem or inteference .... but I don't know what.

Richard
 
Kwik Decision said:
Given that when sailing the op reports that the autopilot works fine I would say it is more likely to be interference from the engine / alternator. Any other problem would probably be present when motoring or sailing.
Click to expand...

Good point, Andy. And we haven't tried on autopilot when sailing but with the engine on. So that's a diagnostic to be gone through. Thanks.
 
I had an Autohelm/Raymarine tiller pilot ST4000 with the control head/display mounted next to the engine control panel.
When sailing under auto pilot all was well. If I then started the engine, the pilot would behave something similar to what you describe: Sharp turn to one side until the ram hit the end stop.
However, if the engine was started first and the pilot then (re)started, it would function as normal.
My conclusion, some type of electrical interference from the engine panel. Learned to live with it.
 
Worth noting that the 6002 is just the control head. All Raymarine pilots that use Seatalk accept the same commands, so the same control heads can be used with any of them and for the majority of installations that's probably a 6002. To find out what actual pilot you have, you need to find the "brain" box.

My guess would be something in the engine electrics interfering with the compass, or possibly its wiring back to the brain. We saw similar symptoms (though permanent, not engine-dependent) when my dad stowed a load of steel beer cans next to the compass.

Pete
 
My money would be on a magnetic interference from the engine causing the repeated altering of course to starboard. If an electrical connection fault the error would be either direction.
Cw
 
BabaYaga said:
I had an Autohelm/Raymarine tiller pilot ST4000 with the control head/display mounted next to the engine control panel.
When sailing under auto pilot all was well. If I then started the engine, the pilot would behave something similar to what you describe: Sharp turn to one side until the ram hit the end stop.
However, if the engine was started first and the pilot then (re)started, it would function as normal.
My conclusion, some type of electrical interference from the engine panel. Learned to live with it.
Click to expand...

.....and keep your mobile phone away from the control head too.
 
Sounds to me like a fluxgate compass problem, if it's a 6002, then this a separate unit mounted somewhere away from magnetic interference, and you often have to move the fluxgate around to find the best spot. On my Southerly lifting the keel (2.5 tons of cast steel) would change the compass heading by 90 degrees. I spent a lot of time moving it around, but eventually gave up and installed a new EV1.
Because it works when sailing, my best guess would be either magnetic interference caused by the engine/alternator/wiring or a loose connection somewhere, either in the fluxgate compass or the wiring to the ACU, the box which drives the rudder actuator, whatever that might be. The ACU you have is probably an S3 or an SPX30, both of which are "Legacy Devices", ie no longer supported
 
Ian_Edwards said:
Sounds to me like a fluxgate compass problem, if it's a 6002, then this a separate unit mounted somewhere away from magnetic interference, and you often have to move the fluxgate around to find the best spot. On my Southerly lifting the keel (2.5 tons of cast steel) would change the compass heading by 90 degrees. I spent a lot of time moving it around, but eventually gave up and installed a new EV1.
Because it works when sailing, my best guess would be either magnetic interference caused by the engine/alternator/wiring or a loose connection somewhere, either in the fluxgate compass or the wiring to the ACU, the box which drives the rudder actuator, whatever that might be. The ACU you have is probably an S3 or an SPX30, both of which are "Legacy Devices", ie no longer supported
Click to expand...

OK Ian, thanks for that. I'm away from the boat for 10 days, so will review on my return. Interestingly, the fluxgate compass is quite close to the engine (2-3 feet) as opposed to the setup on my Rival, where it was about 3m away.
 
alisdair4 said:
OK Ian, thanks for that. I'm away from the boat for 10 days, so will review on my return. Interestingly, the fluxgate compass is quite close to the engine (2-3 feet) as opposed to the setup on my Rival, where it was about 3m away.
Click to expand...

Try a hand bearing compass around the vicinty to and if you get significant deviation move the fluxgate.

Still not sure the compass is the issue as how would it work out it was off course if the compass was taking it off course.
 
I've now got Nordlys back in the water.

We have tried the following>

a. Under engine alone - autopilot does 250 degrees turn to Starboard, then gives the " off course " message.

b. Under sail, works fine -although not yet set up for input from wind instrument (I have replaced the old analogue instrument with a Raymarine I40).

c. Under sail, but with engine running - OK.

The fluxgate compass is about 4 feet from the engine - and I will check tomorrow that thee is no great influence caused by this.

My initial thought is to run through the factory calibration to see if there is anything which jumps out at us.

Any other good ideas - gladly received!
 
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