Autohelm 4000 + moody 34

[scruff]

I sail on a moody 34 equipped with an ancient autohelm 4000 driving a belt on the wheel.

The autohelm works great whilst motoring, but fails when sailing - boat heals over the slightest amount, an alarm in the autopilot sounds and the system stops trying to steer & the boat rounds up.

Is this something which a newer (possibly quadrant driven) autohelm would cure?

Am used to a folkboat plus navik servopendulum which worked a charm. This set up is proving irksome.

Thanks

 

[Fr J Hackett]

In answer to your question, would a below decks autopilot cure the problem, YES.

 

[Graham376]

In answer to your question, would a below decks autopilot cure the problem, YES.

On a 346 (same hull) it made it better but didn't cure it as these boats are directionally unstable. Our 346 came with a wheel pilot which was pretty useless except in the most benign conditions so replaced it with a linear drive on the quadrant. Much better and faster operation but, slightest change in wind speed and the boat would change course faster than the pilot could react and then when wind speed changed again, it would overcompensate, leaving the wake a lazy S. Not surprisingly, the PBO/YM 346 used boat test said something along the lines of "the boat would change direction for no apparent reason". Disliked performance enough to get rid of the boat.

 

[James_Calvert]

Notwithstanding any

 

[James_Calvert]

Peculiarities of the boat, I don't think the Autohelm performance should be that useless.

I had a problem with my 2000 which has a similar box. It would randomly, it seemed, switch to standby. Turned out to be an intermittent power connection in the boat's switch panel.

 

[James_Calvert]

And we used to sail in company with a Moody 34 with the same set up. I don't remember the owners having similar complaints. And I helped deliver her across Lyme Bay with a 5 or 6 on our quarter and never noticed any undue problems handsteering.

 

[jwilson]

A good quadrant-ram autopilot is so much better than any wheelpilot. Re Moody 34/346 - I have sailed one and whilst I found it lacked "feel" on the helm, and didn't easily find a relaxing "groove" to windward, it wasn't that bad and actually sailed quite well. And the aft cabin was very comfortable indeed.

 

[Graham376]

And we used to sail in company with a Moody 34 with the same set up. I don't remember the owners having similar complaints. And I helped deliver her across Lyme Bay with a 5 or 6 on our quarter and never noticed any undue problems handsteering.

Hand steering wasn't a problem as you can feel the boat tucking up or falling off a bit and easily correct as soon as it's felt. I find standing behind the wheel for long periods quite tedious so our Autohelm does 95% of the steering. The boat we have now has exactly the same system (now outdated ST5000) but behaves much better.

 

[SAMYL]

It sounds as if you may have a power failure/reduction when you are sailing and the engine is off, so no charging to keep the voltage up.
Check all your connections carefully especially where the wire goes into the end of the motor at the plug.
Is the whole system fused? If so make sure the fuse contacts are clean too.

I had one of those on my W33, which was very similar, and it worked a treat, but was susceptible to low voltage. They do require a basin full of amps to work satisfactorily.

 

[scruff]

Thanks all, I'll be honest and say I'm not sure I agree with the comments about the directional stability of the boat. We have decent sails and she tracks really well when manually helmed.

The issue seems to be when she heals a few more degrees in a gust, the autohelm fails to react to the adjustment on the wheel nessesary to keep here on track and shuts down.

I'll investigate power line continuity and battery voltage.

Thanks

 

[James_Calvert]

Would also be simple to check all is well with the control box. Unrig it and hold it in your hand, then tilt it appropriately to simulate a sudden heel.

There's a gimballed flux gate compass inside. It could be a problem if it's stuck.

I have a tiller pilot. It sounds an alarm if the tiller arm is pushed over on full deflection, and the boat isn't responding, typically if I've taken it off the tiller without pressing standby. Perhaps your wheel motor could be responsible for a similar effect if the mechanism is slipping somehow?

 

[GrahamD]

The 4000 course computer and software are fairly basic compared to more modern models. Our Marcon 34 came with a 4000 and wheel pilot, and we had similar issues, but replacing it with the Evo 100 unit with wheel pilot has massively improved performance. Changing to the model with below deck ram would probably be even better

 

[scruff]

The 4000 course computer and software are fairly basic compared to more modern models. Our Marcon 34 came with a 4000 and wheel pilot, and we had similar issues, but replacing it with the Evo 100 unit with wheel pilot has massively improved performance. Changing to the model with below deck ram would probably be even better

That's interesting Graham, did you just replace the head unit and keep the existing wheel pilot drive?

 

[White_Belle]

We have a Westerly Tempest 31 with an ST4000 / ram on the tiller. We have found exactly the same symptoms - very frustrating. I think we will be upgrading to one of the new ones this Winter

 

[Plum]

I sail on a moody 34 equipped with an ancient autohelm 4000 driving a belt on the wheel.

The autohelm works great whilst motoring, but fails when sailing - boat heals over the slightest amount, an alarm in the autopilot sounds and the system stops trying to steer & the boat rounds up.

Is this something which a newer (possibly quadrant driven) autohelm would cure?

Am used to a folkboat plus navik servopendulum which worked a charm. This set up is proving irksome.

Thanks

Is the control box fitted at the correct orientation? Because it has a gimballed compass inside there is a limited angle at which it can be mounted.

Www.solocoastalsailing.co.uk

 

[GrahamD]

That's interesting Graham, did you just replace the head unit and keep the existing wheel pilot drive?

I replaced the lot but kept the old wheel drive as a spare.

Today, in a bit of a lumpy sea off Salcombe we were on a dead run in about 7kts wind. I goosewinged the Genoa without a pole and set the autopilot to Windvane mode. The pilot managed to steer to keep the Genoa flying really well.

 

[crackle]

sounds like a problem with the fluxgate compass gimbles.

 

[scruff]

Just finished my annual holiday cruise and thought it appropriate to update this thread.

After the autohelm not working last year I took it apart to see if I could find anything wrong.

The unit is control head & computer in one box. Operation seems to be power into unit, does its course calculation then sends full power, not just signal, to the wheel drive.

What I found was the power into the unit was of expected thickness wire of around normal household appliance cable thickness. However the power cable between the PCB board and the deck plug was of fishing monofilament line thickness - around the same thickness of individual wires in an Ethernet cable. I presume someone rewired it thus this at some point. This would throttle the power getting to the wheel drive, hopefully causing the drive to stall.

So I installed new cable from fuse board to deck plug / new deck plug / deck plug to pcb. Then again from PCB to deck plug, / deck plug to wheel drive motor. I also installed a new drive belt.

Low and behold, the autopilot now works a charm! Sailing across the minch the other day, down wind in 14kts with 1.5m waves on the stern quarter and the autohelm sailed her perfectly as I sat in the sun on the foredeck for 2 hours! It's been a simiar story sailing upwind too.

I'm just a little bit chuffed!

 

[White_Belle]

Thank you for the update, I'll have a look !!

 

[James_Calvert]

Thanks for keeping us posted.