ST4000 Autopilot problem.

[Honeyman]

So we're cruising along (Hunter 35.5) with the ST4000 engaged, light wind, calm seas on protected bay, long straight run of almost an hour, and out of the blue the autopilot takes a hard left turn of at least 45 degrees. It then proceeds to correct itself, bit by bit, and gets back on original heading. Approx. 40 minutes later on opposite tack it does the same thing, but possibly more extreme at closer to 90 degrees off-course and is much slower to try and correct. Disengaged and hand steered rest of afternoon. All other functions seemed fine. Any thoughts?

 

[DanW9494]

Working a problem

That sure takes out all the benefits of having an autopilot, if you can't trust it. Like having your 5 year old steer while you change the jib.Pretty soon the people who have experience will chime in, but i'll go out on the limb since my job involves solving problems. Actually, we don't usually solve problems, we just improve them as much as possible. I've never seen an ST 4000, but i'm writing this from a Holiday Express.Having it twice in the same day rules out not having a problem. So the cause is usually internal or external. If it's external to the autopilot, it might be a fluctuation in the electrical system (think bad, loose connections, a drain from something else in the electrical system drawing too much juice suddenly), a fluctuation in the magnetic field (don't know how the compass works on this unit, but a nearby speaker may be going bad), or something in the steering system (not likely from description of going opposite ways).If it's not external after smarter people weigh in here, it's internal. Which means send it in to get fixed, replace it, or do without. Unless you know how to do surgery on the thing. Cause what you need most of all is peace of mind when you change your jib, or have family on board, or go out in moderate to heavy conditions, or don't have your hand on the wheel.

 

[higgs]

Bad news

I had a Simrad tiller pilot do pretty much the same thing. I checked connections, power supply, wrote posts, talked to Simrad, sent the unit in for testing, and never solved the problem. Sometimes the auto pilot worked great, but other times it worked like yours. I finally just accepted that it was not going to work all the time and learned to enjoy the times it did work. I have a new boat now and the Autohelm 6000 works great.

 

[Pretender]

Just an idea.

It could be something simple like your refrigeration unit turning on. You might have to move the compass further away from the unit.RG.

 

[Ernie]

Same thing happened to me...

The same thing happened to me whenever I turned control over to the autopilot to be steered by the course on my GPS. I emailed Raymarine tech support and they were baffled. Everything was hooked up properly, and except for the "unscheduled course changes", all other functions were good.Here's how I fixed it. If your unit is one of the "newer" ones, you have a cable that runs from the GPS (or plotter, or whatever)to the autopilot. The autopilot has two input locations for this cable. One is on the control head, which is where I originally had it hooked up, and the other is on the course computer unit. I changed the connection to the course computer and the problem went away.You didn't mention if you were trying to run under the same situation or not, but it would certainly be worth a try.Ernie

 

[Bill Roosa]

Check on concurent boat activities

Sounds like a clear cut case of demon infistation. Did you fix something recently and make the demon change his location? Pretender has it right. Look for something that changed; reefer turned on/off, wife went to head and played with styling iron, kids played near flux compass with the spare anchor..... It does not take much current flowing in a wire to upset a flux compass. Now if you where using the GPS for course input then I'd say there is some wiring glitch that is not well documented.

 

[Monty Miller]

Similar experience

Snap the rings apart and check the condition of the belt and clutch. Make sure there is no dirt or spider nests that can cause the clutch to improperly engage or disengage. In our case the clutch needed adjustment because the belt would slip on occasion causing the ST4000 to act like yours did.. Unfortunately Raymarine says that the clutch can only be adjusted by them. The newer ST4000 MK+ is user adjustable. I opted to replace the the ST4000 drive with the MK model which was compatible with the old fluxgate and display. No problems now. I hope this helps.

 

[Reudi Ross]

handheld VHF

If I use my handheld too close to the control head my 4000 MK2 does wierd things.

 

[Don12364]

Ideas

I have a ST6000. It makes a 90° to starboard if someone makes an outgoing call on VHF - I presume the antenna cable in the mast 'talks' to the wind instruments and this back feeds.The symptom of a sudden course alteration and a gradual recovery is what autopilots do when steering to a waypoint under GPS control. The GPS needs to be disrupted or have a 'dodge' inserted first though.I have also had sudden course errors in areas of known magnetic disturbance and these self corrected in time.Once in a Dutch canal we crossed over a motorway and the steel reinforcing in the bridge dragged the magnetic compass round and we turned suddenly also.

 

[Patrick]

Could be one of a bunch of things....

I have a an ST4000 and over the last 6 years have replaced the entire system bit by bit.From what you wrote, I think the problem is either the control head, (they do get water in them), or the flux gate compass.as an aside, when I replaced the wheel drive to the newer model, grey in color, different belt, I had to tie down the locking lever with a piece of string for about a year until it broke in.

 

[Alex]

Wind Vane

That's why I am considering a wind vane. Usually when you sailing you want the best speed possible. It is dangerous to use autopilot when you are running. When you tack or in tight quarters you want to steer yourself. I used an autopilot to tack in heavy air once and it almost killed me. If you are motoring, you should keep your eyes peel anyway.I personally trust electrical stuff less than mechanical stuff.My $0.02.

 

[Ernie]

oops! i read it too fast

I guess I read through the post too quickly. I was talking about having the same problems with the newer S-1 model, not the ST6000. Sorry about that, got confused.Ernie

 

[AXEL]

If had similar problem

Both a friend and myself have the ST4000. On her boat is was a simple fix, I just removed the wires to the flux gate compass, cleaned up the terminals and she was back in business, never happen again. On my boat I experienced the problem because I had stowed some magnetic materials near the compass, while I was sailing the gear shifted and the boat turned.

 

[Tsehum Pete]

Handheld VHF

My Standard Horizon handheld sends my Autohelm ST4000+ hard to port if tranmitted too near the helm. Moving further into the cockpit by the companionway and it does not effect the autopilot.