Magnetic declinations changing?

[likwid]

Originally Posted by Roger

Morone, I think you need to have your compass swung by a pro.

You should have this done regardless anytime you install a compass.

Unless of course you really like rocks.

[Redsoxticket]

sallty
the diameter of earth is 7900 mi.
10,000 is about 2 mi

arctan(2/7900) = .0145 degree

not even 2 hundredith of a degree

[MoroneSaxatilis]

Originally Posted by likwid

You should have this done regardless anytime you install a compass.

Compass was swung when first installed.

Originally Posted by likwid

Unless of course you really like rocks.

I would never rely on just a compass to stay clear of rocks. I've been a crew member on commercial fishing vessels since the late seventies and operating them since the late eighties. I've been operating my own pleasure craft in and around Buzzard's Bay, The Elizabeths and Vineyard Sound since the mid eighties, including more times than I wish in dense fog with no radar.

I haven't run aground (yet).