Deviation (Too Much) on Compass

[David M]

For an inspected vessel, the maximum allowed is 10 degrees in the deviation table.

There are three sources for error, the compensating magnets are not adjusted well enough (or there are no compensating magnets at all), there is iron in the vicinity of the compass or you have DC current in the area creating a magnetic field.

You can always hire a compass adjuster to come out to the boat to properly adjust the magnets. Any DC wire in the area you want to twist the pairs around each other. Keep magnets at least a good two meters away from your compass.

[daddle]

Stainless bolts are suspect too. It's is not a rule that stainless is non-magnetic, it's a tendency. I'd use plastic, bronze (with isolation) or aluminum fasteners.

Experiment in the general area with a handheld compass...although they will affect each other.

[David M]

The cheap stainless has more iron. Test your stainless with a magnet. If a magnet does not stick a compass magnet even further away will not sense the same stainless fastener.

[captainKJ]

i still think it might be the singing

[zeehag]

Originally Posted by captainKJ

i still think it might be the singing

could well be--mine makes porpoises run away....
and all that amalgam must not help compass calibrations...

[cwyckham]

Originally Posted by flpplfflp

Hello Michael

Please se my former answer to captainKJ about the magnets. What I mean with one heading is: If I compensate the compass to show the rigth heading in west it's out of alignment in other directions.

Regards FLPPLFFLP

I'm confused by this. It sounds like you haven't gotten into the console yet to be able to adjust the compensation magnets due to frozen bolts (likely to be two of the magnets in there somewhere)? So what do you mean by compensating the compass to show the right heading west? The only way I know to do this is with the magnets inside. Can you describe exactly what you're doing to compensate and how you know that you are dialing in the right heading (where is the "correct" heading coming from?).

[daddle]

Originally Posted by David M

The cheap stainless has more iron. Test your stainless with a magnet. If a magnet does not stick a compass magnet even further away will not sense the same stainless fastener.

It is more complicated than "cheap" or "Chinese" or 304 or 316 or how much iron. One must test the fasteners if they are near a compass. Personally I'd avoid stainless close to a compass. It's simpler.

Here's the facts.

[David M]

Read the instructions provided by the manufacturer on how to adjust the compensating magnets. It is not as simple as messing with them until you get the correct heading on a particular cardinal point. There is a specific order and method to adjusting them correctly. You cannot guess at it and get it right.

Compensating magnets can compensate out local stainless steel fasteners. This is what they are partially for. Just don't put in different fasteners after doing the compensation without creating a new deviation table.

[flpplfflp]

Hello David

Thanks for your advice. From the comments I get on the topic I supsect the magnets in the compass.

[Cheechako]

Do you have a high output alternator? Ihad one boat that the first 20 minutes of output threw the compass off....

[flpplfflp]

Hello captainKJ

I have uploadet a picture under photos, compass Marco Polo, Kirie Feeling 1350. Sorry not the worlds best, but what I have before getting to the boat again.

Regards

[svcambria]

Originally Posted by cwyckham

I'm confused by this. It sounds like you haven't gotten into the console yet to be able to adjust the compensation magnets due to frozen bolts (likely to be two of the magnets in there somewhere)? So what do you mean by compensating the compass to show the right heading west? The only way I know to do this is with the magnets inside. Can you describe exactly what you're doing to compensate and how you know that you are dialing in the right heading (where is the "correct" heading coming from?).

My very same confusion. Sounds like some kind of user applied compensation...

Michael

[Cheechako]

Even the best stainless when cold worked without subsequent heat treatment will become magnetic. It has to do with the alignment of the grain structure, not just the amount of iron...

[captainKJ]

I still think it is the singing,,,might want to try humming instead

[flpplfflp]

Hello
cwyckham

I have uploadet a photo (see former answer). The problem is the steering console. The Compass is fastenet (from below) to a top plate on the console. I can't get the top plate off the console.

Regards