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Autopilot

Bob S

.
Sep 27, 2007
1,479
Beneteau 393 New Bedford, MA
My new to me 2003 B393 has a RayMarine ST6001 with linear drive, probably dealer installed. It was flawless last season.
The fluxgate compass is in the port aft lazerette with the control head by the instrument panel. I will try to locate the course computer this evening. The system has been making very small moves to port then a large turn to starboard. This past off season I installed a Blue Seas ELCI and a galvanic isolator in that same area but at least 3 ft away. I also installed dinghy davits. I am thinking that maybe they might have caused interference with the fluxgate compass. I am going to check all the connections to rule out corrosion and try re callibrating the unit tonight. Any other suggestion???
Sailed for 3 hours in 60° rain behind the wheel. Not too fun!!
 
Feb 14, 2014
4,304
Hunter 430 Saba Waveland, MS
Any other suggestion???
Calibrate your Flux Compass per manual, then decide the offset from your steering magnetic compass. Make the offset.
Then tune you AutoPilot per the ST6000 manual.
Jim...
 
Jan 22, 2008
7,262
Beneteau 323 Annapolis MD
The compass does NOT want to be near metal, and that's likely a problem.
 

capta

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Jun 4, 2009
3,410
Pearson 530 Admiralty Bay, Bequia SVG
I believe a galvanic islolator is a couple of big electrical coils with iron or steel cores? 3' may not be far enough away, by a considerable amount.
 
Jan 11, 2014
4,776
Sabre 362 113 Fair Haven, NY
I believe a galvanic islolator is a couple of big electrical coils with iron or steel cores? 3' may not be far enough away, by a considerable amount.
Galvanic isolators are just diodes.. no coils of wire..
Both Right. Most of the GI's that we put in our boats, the $300 versions are diode based, iirc, there are 4 diodes in them.

The ones @capta refers to accomplish the same thing only better, but are about $800. These pricey ones are isolation transformers, which do consistent of a lot of iron and coils of copper wire. These are better because there is no physical connection between any of the 3 legs (Hot, Neutral, Ground) between the boat's AC circuits and the shore power circuits. But they are big, heavy, expensive, and overkill for most of us and our budgets.
 
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Bob S

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Sep 27, 2007
1,479
Beneteau 393 New Bedford, MA
Last evening I removed the compass to see if the gimbals might have broken and it looked good. Traced the wiring back to the course computer and removed them to do a test. According to Raymarine I should get:

Red to Green - 4 ohms - I got 4.8 ohms
Red to Yellow - 4 ohms - I got 4.9 ohms
Green to Yellow - 8 ohms - I got 8.2
Screen to Blue - 8 ohms - I got 8.0

I would assume these are good readings. I'm hoping one of you electrical guru's will correct me if I'm wrong. After re-installing the wires I powered up the autopilot and played with the control head. When I activated "auto" the wheel stayed steady where as before I got multiple 1/2 inch turns to port then a large turn to starboard. It didn't happen. I will do a sea trial Friday and calibrate if necessary.
 

jviss

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Feb 5, 2004
3,934
Tartan 3800 Westport, MA
Those readings look good to me. Maybe there was a poor connection that you corrected in the process. It would be much more satisfying to have found a "smoking gun," though.
 
Oct 22, 2014
11,298
CAL 35 Cruiser Portland OR, moored EVERETT WA
@Bob S I had company. She was down in the cabin. She came to the companion way. Took my photo. Then went back inside. Texted our daughter. “Here’s your Dad. I was going to go up and give home a break. But look how happy he looks. Then I thought, this is his dream.”
 
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Bob S

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Sep 27, 2007
1,479
Beneteau 393 New Bedford, MA
We had company and my wife was down below too. She came out for a quick picture but for the most part spent it under the dodger or down below. Lonely behind the wheel in those conditions!
 
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Oct 22, 2014
11,298
CAL 35 Cruiser Portland OR, moored EVERETT WA
So your saying she left the warm dry shelter to photo bomb the image of you at the helm then returned to her place of sanctuary?

All was not dreary at the helm. She showed me the text. We laugher and she brought me a cup of hot cocoa. She was correct. I was enjoying the experience.
 
Apr 8, 2010
1,237
Ericson Yachts Olson 34 Portland OR
The fluxgate compass is in the port aft lazerette
I see a (potential) major problem right there.
That little compass sensor needs to be located very near (as possible) to the pitch and roll center of your boat. While it may not be practical to mount it low on the centerline, behind the mast.... it needs to be close. We could have put ours under the fold-down centerline table, but found a location a couple of feet away. It cannot be close to tools, engines, cans of food, or any other metal. Compromise to some extent is part of the process, but try to install it as close to 'proper' as you can.

On our boat it is out of sight inside the lower part of the molding that supports the nav table, and the cute little Raymarine sticker with the "magnetic warning" is prominent on the visible side.
 
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jviss

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Feb 5, 2004
3,934
Tartan 3800 Westport, MA
It was flawless last season.
This new problem can't be explained as the compass location being less than ideal. It worked previously, and apparently before this owner acquired her. There is some new fault causing this problem.
 

Gunni

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Mar 16, 2010
5,943
Beneteau 411 Oceanis Annapolis
These older compasses work just ok in flat water, throw in rowdy conditions and a compass that is located at the end of the boat and the thing goes haywire. Heck, it even does that when it is located at the center of pitch and roll. Other aggravating possibilities are an undersized drive unit and the settings for course correction. But my bet is still the former.
 

jviss

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Feb 5, 2004
3,934
Tartan 3800 Westport, MA
@Gunni, I hear you, but according to the original poster, something changed. He said it previously worked flawlessly. It's hard to imagine that the fault behavior he describes is related to compass location. Sure, it may be less than ideal, but compass location is not causing a hard turn to starboard!