Winter storage ... Will Compass freeze?

Will a deck mounted compass freeze or otherwise be damaged if left outdoors during the winter? I’m in the Boston, MA area. The boat is wrapped, hung on its side, out of direct sunlight.

no but…
i don’t think that it’s a fluid that freezes at any temps we are going to encounter down here in boston (i’m in rockport, just up 128 a ways, it isn’t water in the compass…if it were, the card would spin a bit faster…see how when you turn, invert or whatever, the card’s movement during sudden shifts of aspect is retarded and has to catch up?

but contact the manufacturer or just look up on-line the specs on the compass…there should be operating temperature specs available somewhere.

No Prob…
I have one of those bungee corded deck compass on my SOF. The SOF was out all last winter. Neither compass or boat was damaged. Off course, I could be wrong and the compass is totally out of whack for all I know… :slight_smile: Nah, last week I headed to what I know is east and the compass agreed.


It should be fine
It probably contains the same fluid as car and aviation compasses, or even a typical pocket hiking compass. I don’t think that the fluid is any more viscous than water, because in extremely cold weather, a “vacuum bubble” will form, and from the movement of that bubble you can easily see that this is a very “thin” fluid. The fluid will not freeze in normal winter temperatures.

Good question Though…
You’re pretty sharp, I’d never even given it a thought…

Compass oil
is typically mineral spirit.

Aqua Meter Compass
is filled with water and will freeze. Most others use mineral oil.

Multiple brunton 70-Ps mounted
and stored outdoors. Like Brother Sing and others no problem!

Remember people use these on sailboats and there are plenty of them outdoors in maine.

Mineral spirits, not mineral oil
There’s a big difference.

at -40 ???
i ordered a 70p which will when mounted on my boat will be in a garage in Winnipeg, getting down to -30 and much more (on extreme occasions). the tech guy at Brunton said the manual cautioned against storing below -30. so for the rest of you whose boat won’t be subjected to artic cold, no worries. for me, i’m not so sure. maybe i’ll be the guinea pig.

I’ll go out on a limb and make a guess
You be the guinea pig, and I’ll present an off-the-cuff hypothosis. We know that whatever is in that compass is not water. And we all learned in high school that water is unique (or let’s be safe for the moment and say “nearly unique”) among liquids because it expands when it freezes (actually, water starts to expand a tiny bit even as a liquid when it cools to a few degrees above freezing, but that’s another story). Normal substances shrink continuously with decreasing temperature, whether in the liquid or solid state. As we all know, the big problem when water in a ridged container freezes, is that it expands and bursts the container. A “normal” liquid which contracts as it gets colder, whether or not it freezes, should not burst the container no matter how cold it gets. Every compass I’ve ever owned developed a void (looks just like an air bubble) in cold whether, and I’m going to guess that if the liquid cools to the point of freezing, it will shrink even more, and there will be a sizable void space within the compass housing. I suppose if the filler material has a lot of tensile strength when in the solid phase, it might distort the compass disk as it cools beyond the freezing point. If not, there should be no problem.

Okay, that’s my guess. So, if by chance your compass freezes this winter, let us all know what happens, huh?

Thanks for the responses!
I will check with the mfg, but it sounds like it should be fine in the Boston area, where we don’t see 0 degrees all that often, and more than 5 or 10 degrees below that is even rarer.


Yep -40 is a different animal
even the lexan starts to get funky that cold. Good luck man Whew that’s cold.

you’re telling me.
truth is that temp is rare even here. in my garage i suspect it doesn’t quite make it there. i also doubt that anything will happen. if they say ‘take caution’ below -30 i bet that they don’t think anything will happen either but it’s such an extreme they are just covering themselves.

as for skin, now that’s another matter. hey at least my friend is professor popsicle the worlds formost hypothermia researcher at the U of M, so i get to watch him push the limits giving me some excitement living in this godforsaken place.


nothing wants to work right…
…in those temps…don’t know how you can stand it. The older I get, the more cold weather bothers me.

A few useful tips here

@BoatBob said:
A few useful tips here

absoutely nothing to do with paddlecraft… a curious first post

@kayamedic said:

@BoatBob said:
A few useful tips here

absoutely nothing to do with paddlecraft… a curious first post

Someone found a 15yo post to promote their new website.

In May…where the misery meter is reading 85 temp!

I drained a Brunton (Silva outside of the US) a month ago and the liquid is mineral spirits. The freezing point of mineral spirits is -94 degrees Fahrenheit. So if the liquid in your compass is mineral spirits you’ll have no problem with it freezing.