Fixing A Leaky Compass

[Jules_M]

Well, it didn't make it through the night. Best I can tell the Aquaseal held up fine on the cracks I applied it to. But it looks like the seal around the perimeter failed. The outside edge of the diaphragm is a bit raggy. Maybe the compression over the years has caused the rubber to lose its sealing capabilities.

Originally Posted by a64pilot

Another source of compass fluid.
I believe aircraft compasses use a purified kerosene

The author of the article I linked above says he only uses purified kerosene. He says you can get it in many hardware stores, sold as lamp oil. Just make sure it's clear. But you have to completely clean out whatever was previously in the compass.

[masonc]

Originally Posted by Jules_M

The author of the article I linked above says he only uses purified kerosene.

Mineral spirits

[stnick]

I went to worst marine and they had a compass guys repair card. Im in Florida The guy was in Largo Fla. He has to certifiy tanker compasses so hes well versed on how to repair properly. My cracked compass has a new glass and no more bubble in it ! Was under 100 . Im Happy to know it was done right . Looks New

[winschwab]

Very old large compass with age cracks in the plastic: excellent results with the above-described method of drilling small hole in top, syringing in mineral oil (cheap drug store variety sold for intestinal relief) and small dot of black electric tape to cover hole.

[GALAWA]

My Plastimo compass was leaking through the diaphragm which had become porous after 20 years.
To the point where 50% of the sphere was air after one summer in the warm Guatemala summer.
I filled the compass with 50% of glycerin. Glycerin does not mix with the desaturated petrol . It is so heavy it remains at the bottom of the compass and, thanks to its high viscosity (i.e. thickness)does not leak through the however porous diaphragm.
With a syringe filled the rest of the compass with desaturated petrol, (what you call mineral spirit, I suppose). This left a 1 ' diameter bubble at the top of the compass I could not reduce further.
I then put the compass in the freeze for the night. At - 15° celsius the desaturated petrol expels its dissolved air and the bubble grows to 2' or 3' in diameter while the flexible diaphragm accommodates the growing volume of liquid + air. (For the same reason a bottle of champagne forgotten in a freezer explodes as the champagne expels its dissolved gas at low temperature)
The next morning, while the compass was still cold, I replenished it with more desaturated petrol, reducing the remaining bubble to 1' diameter again and closed the compass for good.
And voila : the next day the bubble had definitely disappeared as the desaturated petrol back to normal temperature had dissolved and absorbed the gas in the small bubble.
This I did two years ago and my compass is still doing fine with no leak nor bubble.

[Emouchet]

Another one for Viking Compass.

You can ship them the compass, and they will get it back into shape, or, like it happened to me, damages was too important, beyond repair.

[Jules_M]

I tore the whole thing apart today. Cleaned everything. Rinsed what I can't reach in mineral spirits to get all the bits out. Probably screwed the whole thing up. We'll see...

If this doesn't work...

[Jules_M]

Oh boy... I think I whacked the N setting way off and the bars don't help. What should be N is between 330 and 340 degrees, depending on how I play with the bars.

Looks like Option A is to send it in and spend who knows how much to refurbish an old Galaxy Aquamaster and possibly throw good money after bad. Of course Option B is to buy new. I've got a lot of points sitting at West Marine...

[Jules_M]

My last ditch effort seems to be working. It passed the overnight test. No sign of leakage.


After I added the fluid the issue with the compass reading turned out not to be an issue. I'm going to pick up another quart of compass fluid from WM and finish filling it up. The compass takes about 1-1/2 quarts total.

[betwys1]

Originally Posted by Dooglas

Doesn't tell you much on the face of it as something like half of all organic compounds are aliphatic hydrocarbons, but the commonest mixture of aliphatic hydrocarbons is usually called mineral spirits.

Bravo! "Aliphatic hydrocarbon" describes butane methane ...pentane etc..
A typical repair kit for an AVIATION compass includes a small bottle of kerosene (=paraffin oil)