Auto Pilot Excessive Yawing

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DavidGrieves

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Joined
13 Aug 2001
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423
Location
West Cumbria, Cumbria
www.wsandba.co.uk
Hi
I have a Raymarine autopilot its a belt driven wheel pilot with a EV1 sensor and an ACU-100 actuator control unit. However whenever I try to use it, it can yaw from left to right constantly, sometimes as much as 30 degrees each side of my course. This happens when motoring in a flat sea, it is completely useless when trying to sail. Boat is a Bavaria 40 based in Greece.

Can anybody recommend a solution?

Thanks
 
DavidGrieves said:
Hi
I have a Raymarine autopilot its a belt driven wheel pilot with a EV1 sensor and an ACU-100 actuator control unit. However whenever I try to use it, it can yaw from left to right constantly, sometimes as much as 30 degrees each side of my course. This happens when motoring in a flat sea, it is completely useless when trying to sail. Boat is a Bavaria 40 based in Greece.

Can anybody recommend a solution?

Thanks
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Don't know the model, however, have you checked all your settings, could be as simple as the gain being turned up resulting in over sensitivity. I would check all the settings first.
 
Tranona said:
Probably best to go back to the beginning and recommission it following the guidance in the user manual.
Click to expand...

Came here to suggest this. I had to recalibrate a raymarine compass on the last trip as it managed to get itself out by 90+ degrees. Was considering tuning the autopilot whilst the commissioning manual was in my hand but never got round to it!
 
Alex_Blackwood said:
Don't know the model, however, have you checked all your settings, could be as simple as the gain being turned up resulting in over sensitivity. I would check all the settings first.
Click to expand...
I've been all through the menus, there doesn't seem to be anywhere to alter the gain or sea state. The only options are "Cruising- Performance- Leisure" it doesn't make any difference which one I have it on. I did fine a response setting that could be altered from 1 to 15 but again it didn't alter anything.
 
Anything untoward near the sensor? I put a couple of flares within 30cm of mine and it went doo-daa. Not sure why that would be but when I moved them normality was restored.
 
That is a good point. The sensor is probably in the hanging locker in the starboard aft cabin. Lots of things get put in there or the shelves next to it.
 
I had similar with the identical set up. Wheel working continuously from side to side (on a Sigma 362).

To cut a long story short, you have to measure the time it takes to go from wheel hard over on one side to hard over on the other side. Somehow I had entered the wrong figure, once the correct figure was entered, somewhere in the setup menu, it was transformed into an impressive bit of kit.

HTH
 
skip50 said:
I had similar with the identical set up. Wheel working continuously from side to side (on a Sigma 362).

To cut a long story short, you have to measure the time it takes to go from wheel hard over on one side to hard over on the other side. Somehow I had entered the wrong figure, once the correct figure was entered, somewhere in the setup menu, it was transformed into an impressive bit of kit.

HTH
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I've just been looking through a manual on the Raymarine website and I saw that about measuring the time from hard over to hard over, said you had to do it if there wasn't a rudder reference sensor and I'me not sure if we have one fitted, haven't seen one. I'll give that a try.

Thanks
 
Tranona said:
That is a good point. The sensor is probably in the hanging locker in the starboard aft cabin. Lots of things get put in there or the shelves next to it.
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It's mounted on the back side of a cockpit locker and from memory I think there are a couple of electric shore line hook up cables in there. I'll move them to the other locker and see if that makes any difference.

Thanks for your help.
 
DavidGrieves said:
I've just been looking through a manual on the Raymarine website and I saw that about measuring the time from hard over to hard over, said you had to do it if there wasn't a rudder reference sensor and I'me not sure if we have one fitted, haven't seen one. I'll give that a try.

Thanks
Click to expand...

Unlikely (but not impossible\) that you have a rudder sensor with a wheel pilot.

I would do a factory reset, then go through the commissioning process, taking note of the wheel hard over settings.
 
On the Raymarine website it says the ACU100 is suitable for boats up to 7500kg.
I would expect a Bavaria 40 to be at least that. Perhaps the autopilot is under powered?
 
DavidGrieves said:
It's mounted on the back side of a cockpit locker and from memory I think there are a couple of electric shore line hook up cables in there. I'll move them to the other locker and see if that makes any difference.

Thanks for your help.
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Yes, that is a common position. My old 37 had it there as it is both central laterally and well away from the engine but a bit vulnerable. If moving the cables does not help, then back to post#3 and start again setting it up according to the manual. I had to do this twice when I upgraded mine from the original ST 4000.
 
CrikeyChris said:
On the Raymarine website it says the ACU100 is suitable for boats up to 7500kg.
I would expect a Bavaria 40 to be at least that. Perhaps the autopilot is under powered?
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A fully laden Bavaria 40 will be in the order of 9500 to 10000Kg, so highly likely. It certainly will be underpowered in rough weather and have difficulty keeping the boat under control. However it should work perfectly in calm water under sail or power. Definitely sounds like a set up problem.

From memory you should check an magnetic souce (gas bottles) are at least 1 metre away from the compass head. So worth spending some time check what is within 1m.

I have an EV-1 and ACU100 on my tiller steered 32ft Fulmar and it works brilliantly.
 
Displacement guidelines are just that and should have little influence in a flat sea, under power and on a boat with a balanced rudder, particularly with a wheel pilot.

One thing to check for with a wheel pilot is any unusual or excessive play in the steering system.
Also, is this a new situation?
Lastly, does the pilot steer any better in rough(er) conditions? This is not a joke, I had one that couldn't hold course and for the love of God in a flat calm, but steered devilishly straight in rough water.
 
CrikeyChris said:
On the Raymarine website it says the ACU100 is suitable for boats up to 7500kg.
I would expect a Bavaria 40 to be at least that. Perhaps the autopilot is under powered?
Click to expand...
That is correct - and the wheeldrive is way underpowered. However it should cope with motoring and sailing in moderate conditions on a Bav 40 - which is about 7500kgs. The yawing is unlikely to be anything to do with the power of the drive. Its weakness will only show if trying to use it in heavier conditions.
 
The wheel pilot is underpowered for a 40ft boat, but there is no way it should "yaw from left to right constantly, sometimes as much as 30 degrees each side of my course. This happens when motoring in a flat sea "

That is not the description of being under powered.

It would certainly be better with a Linear drive, but the ACU-100 is not suitable for a linear drive, the OP would need to buy an EV200 core pack and a type 1 linear drive at a cost of about £2500 plus a tiller arm or quadrant bracket, plus fitting.
 
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