Bubble in 70P compass

Went out paddling today and realized my 70P compass had a nice dime size bubble. Seems that would indicate a leak or something not good. Others had this problem, any solution, any impact on the usefulness of the compass?


– Last Updated: Dec-22-07 8:54 PM EST –

oil for in the 70 p is a special compass oil. The bubble doesn't really affect anything much but the compass are guarenteed for life so you can just contact GRO and exchange it or wait until Valley or someone that's able to get the oil from Brunton gets around to sending some to GRO and then to you. I believe it's Jason at Valley not Peter that usually deals with this stuff.

Peter might want to answer but the oil actually comes from Brunton.

The compass needs to be put in a freezer, then after awhile , when it's good and cold. The screw on the bottom is taken out and the oil added. sometimes at the factory they are not quite froze enough to create the necessary affect, so you get a bubble eventually.

The easiest is to just exchange it. Any dealer that carries Brunton should be able to do it.

Best Wishes

Oh , I almost forgot....Merry Christmas

Interesting, I guess you are saying here if the compass gets cold enough there may be sufficient suction to draw air in past the fill port; the flexible expansion/contraction joint doesn’t give enough.

A good reason for non-cold-weather paddlers (that would be me) to remove the compass from the boat and bring it inside during the winter. I’d already done this, actually, since it just seemed like the right thing to do anyway.


Cold is the cause, but temporary problem
I had loaded the boat early in 16F in order to go paddling. Day was around freezing on the coast. When I go it back in the basement, the bubble started to decrease and after 24 hours it had disappeared. Suggests the oil shrank to create vacuum as opposed a leak. Time will tell.

It’s not oil, it’s mineral spirits…

– Last Updated: Dec-24-07 9:56 AM EST –

...a.k.a. "paint thinner" (hint: you can tell by the smell). There is nothing "special" about it and you can get it just about anywhere.

Bubble in my Compass
Be careful what you put in your compass. The wrong liquid can eventually disolve the numbers on the compass. Ask me how i know? Vaughn Fulton

believe that it’s silicone based…

Best Wishes


when I broke mine…it was oily.
It certainly wasn’t mineral spirits. I broke mine, and while I can’t say whether it was a specialty product or not, it got all over everything and was oily. I could go with silicone based, but not mineral spirits.

I bought a liquid-filled air-pressure gauge years ago (the liquid damps the pulses from the compressor making it easier to read). The catalog described it as glycerin-filled.

So I thought that’s what might be in these, but don’t really know.


USCG Eagle…
my nephew was stationed on the Coast Guard sailing ship, the Eagle. I mentioned this thread to him, and he told me that the compasses on the Eagle were filled with kerosene.

Perhaps they’ve changed it…
…but the ones I’ve opened (3, IIRC) have all had mineral spirits in them. It’s a slightly oily-feeling fluid with a strong chemical smell. Unlike oils, it will evaporate.

normal for spherical-shaped objects in cold water

You mean my compass might get all wrinkled as well?

I drained my compass last year. I filled it with Ritchie compass fluid after calling Brunton on the phone. I got it from West Marine. They only had 1 quart size. I helped several other friends drain and refill their dirty looking Brunton/Nexus/Silva 70p compasses.

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