"Steve" wrote in message
...
I haven't felt a need to use a hand bearing compass for many years
(pre-radar).

Today I needed to take a bearing on a location ashore, from my boat. The
radar was off and I pulled out my old Richie from the locker. I had
brought it over from my last boat and had inherited it from that boats
previous owner. Never really use it or looked it over.

When I took my bearing, it was obvious that it was off by over 45 degrees.
Took the bearing several times, check the way I was operating the compass
card hold/release button, etc.

Went to the work bench and opened the case (two screws). Ah Ha! The (at
least) 10 year old illumination batteries were still in it. Very corroded,
but this was confined to the battery contacts.

Corroded batteries shouldn't cause a bearing error, however while
replacing the batteries I noted a label that required that the batteries
be "Non Magnetic". Gave two mfg'ers part numbers. The batteries I had
onboard turned out to have a dramatic effect on the compass, as did the
old ones.

So, not only had I neglected to service the hand bearing compass
batteries, but I (or the previous owner) had installed magnetic batteries.

Sure glad I wasn't taking critical bearing that could have put my boat on
the rocks.

Until I can locate a source for these special Non Magnetic batteries, I
will operate it without illumination. (once the compass card is locked, I
can use a flash lite to read the bearing.)

--
My experience and opinion, FWIW

Steve
s/v Good Intentions

Interesting. I've never heard of "non-magnetic" batteries or, for that
matter, "magnetic batteries". Be interested to hear if you find any.