Autopilot Compass Location

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pmeyers's picture
pmeyers
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Posts: 117
Autopilot Compass Location

Last year I installed an ST4000+. This was followed by electronic upgrades, gps, radar, etc. I went through the compass deviation process yesterday and
The deviation was 20degrees,not acceptable, and much different than when I first installed the autopilot. Manual says to relocate the compass, which is currently located under the sink. Is it possible sink is causing interference
Or could it be proximity to fuel tank just on other side of bulkhead. Where have others mounted the compass on a Mark I ? Saw a similar post but dealt only with
Mark II.

Paul Meyers
1986 Catalina 36
Hull #615
Ventura, California

WindEnsemble's picture
WindEnsemble
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Posts: 99

Mine is mounted (installed by a previous owner) about 1 foot aft of the mast just inside the door that allows access to the in mast wiring, etc. Working great in that location.

Jeff

S/V Wind Ensemble
1987 C-36 Wing Keel
Universal M25XP 23hp
Hull #705
Coastal Alabama

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LCBrandt
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Posts: 1282

Paul, the sink could be the culprit.

Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
 

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bboggs
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Posts: 144

I just installed a X5 and the most reasonable place I could find to install the fluxgate compass in the correct orientation was in the cubby under the game table. I had to relocate the tool bag that I normally stored there but its reasonably free of magnetic influence otherwise.

Bill Boggs
s/v Palmetto Moon
1991 C36, Hull 1128
Herrington Harbor South
Chesapeake Bay

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pmeyers
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Posts: 117

Jeff, Sounds like your suggestion might make the most sense although it seems very close to the mast. I think that Larry is right, I amy be getting interference from the sink and possibly fuel tank. Now I hope that I didn't cut the wire short after I installed it under the sink. Bill, I think that we may have different interiors and I don't have the cubby that you describe.

Paul Meyers
1986 Catalina 36
Hull #615
Ventura, California

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WindEnsemble
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Posts: 99

Paul, I thought the same thing when I saw it there, but it does work fine so I'll leave it alone. Good luck.

Jeff

S/V Wind Ensemble
1987 C-36 Wing Keel
Universal M25XP 23hp
Hull #705
Coastal Alabama

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LCBrandt
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Posts: 1282

Paul, the mast and step (and I think the fuel tank, as well) should be aluminum and therefore non-magnetic. Steel, iron and DC electrical cabling are to be avoided. Also beware of stainless steel, as lots of what is used nowadays is cheap S/S alloys from China that are not pure, and are therefore magnetic.

Larry Brandt
S/V High Flight #2109
Pacific Northwest, PDX-based
2002 C-36 mkII SR/FK M35B
 

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manonash
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Posts: 68

Larry,
Yeah - when we bought the boat, our was under sink as well (on a bracket, directly above the aft end of the tapered bilge area). On our delivery trip, I "swung" the compass to calibrate and found that it was 12-14 degrees off (did it three times).

It was in the middle of a bunch of electrical stuff (galvanic transformer, inverter/charger/wiring from solar panels/etc...) All of that couldn't have been great...

So, I moved it into the bilge, directly in the center of the boat (upside down, on a wood bracket the crosses the bilge) and tried it again. Now I only have 1-2 degrees deviation (which is better than my fluid compass, for sure...)

Good luck!

__________________
Steve Ramsey - Puget Sound
S/V Manonash - '96 C36 mkII (#1586) - M35B

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pmeyers
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Posts: 117

I forgot to report back on this:
I moved the fluxgate compass from under the galley sink to the location suggested by Jeff, just aft of the mast but away from the wiring connections for the mast. Had to solder in an extension wire, but it works great now, well under the deviation described by Raymarine. Thanks for your help!
Paul

Paul Meyers
1986 Catalina 36
Hull #615
Ventura, California

WindEnsemble's picture
WindEnsemble
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Posts: 99

Been away for a while myself. Glad that worked for you.

Jeff

S/V Wind Ensemble
1987 C-36 Wing Keel
Universal M25XP 23hp
Hull #705
Coastal Alabama

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gforaker
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Posts: 133

My tech guy strongly recommended putting it just forward of the hanging locker in the v-berth. Crazy long run of wire, but it works well there and far away from any metal.

Gene Foraker
Sandusky Yacht Club
Sandusky, OH
1999  C36  #1786
Gypsy Wagon

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