Compass Deviation Error

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Root
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Compass Deviation Error

Post by Root »

Compass Deviation Error

We are new owners of 2002 PDQ 36 #95 Wind Seeker. We are experiencing a 20 degree uncorrectable compass deviation error. The boat has the original Ritchie HV-76 - Helmsman bulkhead mounted compass installed as delivered from the factory and no new instrumentation has been added in the vicinity of the compass. We have confirmed that the compass is mounted vertically, and aligned with and perpendicular to the center line of the boat. We have owned many boats including a cruising catamaran but this is the first one that we have not been able to correct or develop a reasonable (max. 5 degree E/W error) deviation table for.

Has anyone experienced a similar problem? How did you correct the error?

Ray and Paula Reuter, Wind Seeker #95
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Ed Ellis
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Post by Ed Ellis »

Try taking a hand-held magnetic compass and holding it next to your mounted compass. See if the readings are similar. Then move it side to side, at increasingly greater intervals. There may be something in your instrumentation that's creating a magnetic field.

As instruments get older, resistors & other elements (especially things with motors in them like autopilots) can start going south on you. It may be possible that magnetic fields are being created now that at one time were not present.

It's also possible that the field was there all along with the previous owners, but they did not relaize it because they may have been using GPS / electric compass and never really attended to the old fashioned one.

Maybe someone else can provide some additional insight.

Ed Ellis
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Root
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Compass Error Possible Cause

Post by Root »

Ed,

Although still not corrected, I did discover a strong magnetic interference in the vicinity of the engine throttle/shift cables. A magnet will stick to them. They are gray colored ones stamped Yamaha, but I suspect they are Morse or some other make. I will attempt to balance the magnetic disturbance with other ferrous materials and see if I can correct the error.

Thanks for your advice. I did do exactly what you described and un-mounted the compass moved it aft where it read correctly. I then gradually moved it forward noting an increasing error in it as I reached the mounting point again. My hand-held reacted in the same way.

I will keep you posted on my success or failure with correcting the error.

Ray & Paula Reuter, Wind Seeker #95
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Ed Ellis
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Post by Ed Ellis »

Glad I could help. Ed
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Page 83
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Compass error

Post by Page 83 »

I've had my yamaha binnacle apart quite a few times: there are few steel parts inside, and the bulkiest parts are the handles themselves. You can take them off without opening the binnacle itself, and see if they are the culprits. I'll bet someone here can tell us how to degauss them!
Sandy Daugherty "Page 83" PDQ 36026
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