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View Full Version : Air bubbles in compasses - solution?



Labrador Coaster
04-27-2011, 06:58 AM
Hello everyone,

I have a couple compasses that have air bubbles,

Wondering what is the recommended liquid to fill them back up.

Just my 2 cents but it seems like leaving them aboard the boat during the -30 deg. winters might have something to do with this seal failure, ie; liquid contraction\expansion, I dunno..

I used to follow this wonderful forum religiously a few years back, couldn't get back in using my old password\username, had to reregister. Looks like I have lots of great reading to catch up...

cheers, Wilson

johngsandusky
04-27-2011, 07:45 AM
My compass suffered the same after bringing the boat from Florida. I had it professionally repaired. Do a search on "compass oil" you'll find some sources. I've also read that mineral spirits will do, but I wouldn't experiment. Very old compasses used alcohol, even water, I think.

Willin'
04-27-2011, 08:01 AM
I was going to send my White Constellation to a shop in Mass. for servicing last year, the primary gripe being a bubble. It was going to cost me $250 just to open it up, plus parts as needed. As I was pulling it I noticed one of the screws on the bronze mounting bezel was loose... probably how the bubble got in. After tightening all the screws I let it acclimate to a uniform temperature for a few days in my basement then topped it off with Compass oil (available at West Marine for about $13/ quart IIRC).

Presto, problem solved and saved a bunch o loot to boot.

HR
04-27-2011, 08:56 AM
The first step is to find out what's currently in your compass. Some compasses are filled with mineral spirits and some with mineral oil (and maybe some with other fluids - alcohol as suggested above). Baby oil is mineral oil, although it often has other additives to make it more appealing (almost always a perfume). The perfume doesn't hurt, but other additives (such as aloe vera) might.

One way to find out what's in your compass is to take a small amount of the fluid out of the compass and put it in a clear plastic tube, then added mineral (baby) oil to the tube, shake it up and let it settle. If it doesn't settle into layers then the mineral oil should work. If it does settle into layers, try the same thing with mineral spirits. Once you have found a compatible liquid, fill the compass then put the compass and the liquid into the fridge overnight. This causes everything to shrink up. Once it's good and cold, fill it up again and you should be good to go with no bubbles (assuming that there are no cracks or leaks in the glass or seals).

I did this about six years ago with a Ritchie and a Danforth and both have been perfect since.

wizbang 13
04-27-2011, 09:00 AM
I had an old box compass for years. One day, a chap came aboard who had the same compass and needed to know how I got rid of the bubble. Take a closer look ,sez I.
I had drained the whole thing, no brains/no headache.

Captain Intrepid
04-27-2011, 12:48 PM
Very old compasses used alcohol, even water, I think.

The stories I've heard are sailors used to drain the alcohol out of compasses and top it up with water, leading to the compass card warping and not working so well... Typical of sailors eh?

TimH
04-27-2011, 01:01 PM
I heard the magnetic field is changing and unreliable, Best to stick with GPS :)

John B
04-27-2011, 04:28 PM
Some compass' you'll never beat it. I had a sestrel conquest that had some sort of 'new' 1980's seal which was a product failure/ recall at the time.

TimH
04-27-2011, 04:35 PM
Speaking of compasses, I made a tapered teak trim ring\wedge for mounting my new Ritchie BN202 but I have noticed a lot of people mount their compasses directly to the bulkhead even though it is not perfectly vertical. The trim ring makes it look a little cluttered...thinking of leaving it off.

JimConlin
04-27-2011, 06:06 PM
Speaking of compasses, I made a tapered teak trim ring\wedge for mounting my new Ritchie BN202 but I have noticed a lot of people mount their compasses directly to the bulkhead even though it is not perfectly vertical. The trim ring makes it look a little cluttered...thinking of leaving it off.

The Ritchie BN202 installation manual says it's supposed to be mounted vertically. I'd skip the wedge block only after consultation with the manufacturer. There are some Silva and Plastimo bulkhead compasses that'll tolerate a sloped bulkhead.

I had a Constellation and I dimly recollect 'burping' my constellation of small bubbles by removing the fill plug, pushing gently on the bottom and trying to replace the plug without leaving a bubble under it. It was brought indoors for the winter.

John B
04-27-2011, 06:46 PM
The issue with the sestrel was the 'rubberised' diaphragm reacting with the fluid . I believe thats the mineral spirits type... it was special compass fluid I bought from a compass specialist . The way it first manifested was a colour change to a murky brown as the fluid broke down the 'rubber' and then a leak and a growing bubble. My recollection was that this compass caused massive issues for the company and may have compounded into them actually folding.

Anyway , I fixed it by repacing the diaphragm with a perspex backing plate but the more I think about it surely the oil option is going to be less corrosive than spirits and I could have perhaps used that instead.

oz sailor
04-27-2011, 09:22 PM
I have found in the past with a couple of compasses that were subject to cold conditions and formed smallish air bubbles, was to place them on the dashboard of the car when the sun finally comes out and this seems to eliminate the problem, if the bubbles were substantial then a refill is the only way to go.

Binnacle Bat
04-27-2011, 11:01 PM
The stories I've heard are sailors used to drain the alcohol out of compasses and top it up with water, leading to the compass card warping and not working so well... Typical of sailors eh?

I think the card is brass, and replacing the alcohol with water would be unnoticed until the temperature got below freezing, at which point the card would not swing as freely as good navigation might require.

I inherited a Ritchie compass dating. I think back to 1911. Flat card, gimbaled housing. I wrote to the manufacturer more than 20 years ago inquiring as to the age of the compass and the proper fluid to refill it with.

Ritchie wrote back with the date of manufacture and the name of the distributor.

The letter also said that the compass fluid should be denatured alcohol. If I remember correctly that would be 9 parts ethanol and 1 part methanol (wood alcohol) and an undetermined amount of water. the alcohol acted as an antifreeze, and the methanol supposedly kept the alcoholics from drinking it.

There is a dome in the middle of the card, above the pivot, which I believe had an air bubble in it, when properly assembled, and not tilted beyond the limits of the gimbals. This air bubble served two purposes. One was to provide a compressible gas to minimize the pressure differences caused by temperature changes. The air bubble also provided some buoyancy to the card, to minimize the weight of the card on the pivot pin. Of course the whole purpose of a liquid filled compass is to damp the card from the motions of the ship.

I may once have read how to refill the compass with fluid, and get all the air inside the dome on the card, and none above the card, floating up against the glass and interfering with the balance of the housing in the gimbals and the free swinging of the card. If I did, it has totally escaped my mind.

so it goes

Allan
in the hills

Rich VanValkenburg
04-29-2011, 09:13 AM
I repaired an old compass on the boat I was crew on several years ago and went through the 'what is this stuff?' experiments. Ya know, I can't even remember what make or model it was but I do remember that the liquid was pretty flammable. I don't know why I tried this but I dipped a toothpick in the existing fluid and it lit right up with a match. After all of the compatibility tests were finished I found that the only suitable match was clear lamp oil.

TimH
04-30-2011, 01:05 AM
Ritchie BN 202 mounted on my Typhoon.

http://i477.photobucket.com/albums/rr133/hoehnt/rissa20jpg.jpg

Labrador Coaster
04-30-2011, 06:55 PM
Thanks guys for the info,

I will indeed do a ''taste test'' to see what is in there presently. I have mineral oil that goes in the base of my dive compressor, that should do the job. Was concerned about using more toxic stuff ( like alcohol), thought it might warp the card, eat the paint off the #'s, etc.

Wooden Boat Fittings
04-30-2011, 08:35 PM
One method I've heard of (but never tried) for determining whether the liquid is alcohol or oil is to dip a scrap of paper into it. If the wet corner dries out without signs if immersion then the liquid is alcohol, but if dries out and leaves the paper transparent then it's oil.

I have an old and now completely liquid-less hand-bearing compass -- the original liquid content of which I therefore can't determine -- which I propose filling with mineral oil (called liquid paraffin here) when I get around to it, as I think it will better dampen the card's movement than would alcohol.

Mike