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Old 04-11-2016, 14:01   #16
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Re: Autopilot failure rounding South Africa

He's right on suspecting the motor. Could be something besides the brushes, but my guess is it's the motor. Surprised you don't have a spare.

Could possibly be the control head as you can't rule that out as I have in the past and still had motor issues.
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Old 04-11-2016, 14:06   #17
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Re: Autopilot failure rounding South Africa

Gaia,

You mentioned the problem occurs in big winds and seas, when there is a lot of weather helm. Have you done the experiment of adjusting your sail plan for less wx helm? if you have, and it didn't help, it does sound as if something is in the way of reliable magnetic feedback to the unit. One way we ease things for the autopilot on our boat is to travel the main down a bit. So, as yet, I'm not convinced that you don't need to baby it a bit.

However, the issue of ferrous material somewhere near the compass could also be an issue. For instance, on our boat, the battery for the Milwaukee rt. angle drill that we use on the genoa sheet winches has only two places it can be in the cockpit without affecting the autopilot. We have had to re-arrange some stowage to help the AP work better.

Another way to approach the problem would be to consider a windvane. One of the great things about them is that they need no power, except that provided by the wind, and they are silent. We've sailed a few 10s of thougsand miles with one. With a light fast boat like yours, you do have to be careful with one off the wind, but there are many times it will steer the boat in a trouble free way.

Ann
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Old 04-11-2016, 14:33   #18
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Re: Autopilot failure rounding South Africa

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Originally Posted by Neptune's Gear View Post
If it jumps, or is not linear, the rudder angle sensor is the route cause. Try this, report back.
Like he said. I have dealt with two rudder angle sensor failures recently, and several in the past. It can seem as if they are ok when you wiggle things around.

One was giving drive fail alarms (on the latest Raymarine series controller) when just starting to get going in larger waves. On inspection it was just a bit wobbly, disconnected if from the quadrant and moved it manually and it jumped around fairly erratically.

The second one was moving in calibration and would not return consistently to centre. This was picked up when the dockside wizard kept failing the rudder calibration with a message something like "inconsistent readings".

It could of course be something else but well worth checking these out.

On the charter boats that I maintain we send the motors in for service usually annually and the brushes are changed as routine... but we do 30k miles a year on those !

Other than the above we have very few problems with the Ray pilots.
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Old 04-11-2016, 21:20   #19
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Re: Autopilot failure rounding South Africa

Hi all

Some good suggestions and thanks for them all. I will follow them up!

A couple of additional comments: the reason I am not suspecting the motor or drive units is that there is no lack of response. The rudder is being moved excessively for the correction needed and then just as excessively back as though the unit is saying "oops, overdid that, oops" and so on and the drive obeys.

I have a spare drive and a spare motor for the drives.

I also have a spare rudder sensor which I can try but the one in place changes resistance smoothly and repeatedly and I need to be running in stronger winds to test which will mean going to Durban from here and not returning. Deliveries to SA can take a long time and we will have only two months left on our visa after Durban.

The suggestion of increasing the resistance manually to simulate weather helm is intriguing and I will try that. We of course pay a lot of attention to weather helm often running under foresail only in strong following winds.

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Old 04-11-2016, 21:57   #20
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Re: Autopilot failure rounding South Africa

One more comment: in my original post I incorrectly wrote that the heading shown by the gyro compass was off. The heading shown is of course not from the gyro but from the fluctuate compass.

Jim
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Old 04-11-2016, 22:26   #21
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Re: Autopilot failure rounding South Africa

Sorry, fluxgate! You should see what my autospeller changes foresail to!

Jim
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Old 05-11-2016, 05:01   #22
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Re: Autopilot failure rounding South Africa

Quote:
Originally Posted by Gaia View Post
Sorry, fluxgate! You should see what my autospeller changes foresail to!

Jim
Since auto spellers can learn intelligently these days, I'm hoping you're a mohel!

Good luck with the repairs and the journey.

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Old 05-11-2016, 07:24   #23
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Re: Autopilot failure rounding South Africa

Where are you Jim?
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Old 05-11-2016, 12:28   #24
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Re: Autopilot failure rounding South Africa

We are in Richard's Bay South Africa. Arrived here via Sumatra/Mascarenes/North Madagascar and the Mozambique Channel. GAIA is a steel Tom Colvin designed Gazelle junk rigged as a schooner. She sails well off the wind. Before our AP failure we had a 200nm day sailing partially reefed. We learned long ago that sailing conservatively is easier on her as well as on us.

There is an agent for Raymarine in Durban only about 90 nm south of here. He suspects gyro failure on the S3G course computer and the absence of a gyro on the S3. I am dubiously hopeful. May be able to do some tests in the harbour on Monday.

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Old 05-11-2016, 13:05   #25
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Re: Autopilot failure rounding South Africa

Jim, this may sound like a dumb question, but have you re-calibrated your AP since you changed the fluxgate?

If your visa is due to expire, you can apply for an extra 3 month extension with Home Affairs.
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Old 07-11-2016, 05:24   #26
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Re: Autopilot failure rounding South Africa

We had similar issues several years ago and after extensive tracking found to our amazement that a new replacement bilge pump had been stored on a shelf over the flux gate compass........once moved all went back to normal....
It happened...check out the area around your compass.
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