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unbusted67 30-03-2011 12:36

Heavy Deviation
So I just made up an impromptu deviation table just using my GPS's compass (for a look at a discussion on that please see here:

This is a fairly inaccurate method but it did serve the purpose of highlighting some glaring discrepancies. I have deviation up to 20 degrees on some courses, and as much as 10 in the other direction. There is an older model Furuno radar about 2.5 feet away that I suspect is causing much of the issue, I can't really move it that easily though because it is one of our primary navigation instruments. Am I going to be able to get this compass adjusted or am I going to have to rethink my entire electronics situation?

unbusted67 30-03-2011 19:16

Re: Heavy Deviation
Hello? Anyone out there?

speciald@ocens. 30-03-2011 19:20

Re: Heavy Deviation
My wife put her thigh master next to the electronic compass - you wouldn't believe the deviation.

atoll 30-03-2011 19:47

Re: Heavy Deviation
in thailand you have to be really careful with some of the girls.
allways check their ground tackle,or you might find a lot of deviation.........

Jim Cate 30-03-2011 20:59

Re: Heavy Deviation
Nearly all compasses have built in compensation magnets. It is possible that yours have been tweaked incorrectly, or that they simply have not been adjusted to minimize deviation. You will most likely be able to remove much or even all of your current deviation by going through the ritual of adjustment. Your compass owner's manual (if available) should outline the process, or one can find non-proprietary instructions on line.

Let us know how it turns out, and good luck, too!


Jim and Ann s/v Insatiable II lying Morning Cove, NSW, Oz

SteveA 30-03-2011 21:41

Re: Heavy Deviation
As a general rule of thumb, 1 metre would be the minimum distance for a magnetic compass to be positioned away from a source of electricity. Your radar, as you say, is probably the source or your problem.

Did you swing the compass with the radar on or off ?

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