# Bubbles in magnetic compass



## Archie2009

Had a bubble the size of a thumb in the standard magnetic magnetic compass. So topped it up with a little distilled water. Got rid of the big one, but got a few very very minute ones. Just left it at that. 2/o was very keen on getting it absolutely bubble free. So let him try. But after a few attempts he gave up. Then closed the plug. Any ideas on how to get rid of these, or should I just let them be?


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## surfaceblow

I always thought that alcohol or mineral spirits was used in the compass. The instrument shop that I did business with would hold the instruments at 28 in Hg for 15 minutes after servicing and refilling to remove air bubbles. 

I remember Isopar L being in the Exxon Mobil Products listing. It's stated use was for dampening compasses and other instruments but it was not on the ships lubrication chart. 

Joe


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## david_crosby

Archie2009 said:


> Had a bubble the size of a thumb in the standard magnetic magnetic compass. Any ideas on how to get rid of these, or should I just let them be?


A constant problem on Manners tramps. We used to use Stolichnaya Vodka or (at a pinch) Tanqueray Gin. Open the plug and top up as much as possible, leave the plug open o'nite and repeat until the meniscus on the liquid inside the plug hole remained constant. Close the plug and dispose of the rest of the liquid thoughtfully


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## slick

All,
In to the Medical Locker and 'borrow' one of the Hypos and some Gin and away you go.

Yours aye,

slick


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## borderreiver

You need a small bubble to allow for expansion and contraction due to changes of temp. the expansion chamber can not cope with large changes..
Have seen the mixture freeze due to using the wrong mixture and sediment in the mixture . (the gyro failed at the same time. Boat compass used) The compass had just been returned from a leading nautical instrument maker


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## NoR

Yes I always thought that the bubble was necessary for expansion, and the fluid a mixture of distilled water and alcohol. There were folk tales about alcoholics drinking compass fluid.

The Standard Compass was usually dry card and the steering compass fluid damped for easier steering..........I think?


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## mikeg

Interesting thread. Is there a recommended fluid viscosity for card damping or is the mix of distilled water and alcohol deemed sufficient. The alcohol I assume is there as antifreeze, can you not just use vehicle antifreeze or is colour/viscosity the problem there?


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## bev summerill

Always signed for a botle of gin from the steward for removing the bubble then drank the rest
Bev Summerill


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## JoK

NoR said:


> Yes I always thought that the bubble was necessary for expansion, and the fluid a mixture of distilled water and alcohol. There were folk tales about alcoholics drinking compass fluid.


When I was a kid, there was a compass in my Grandfathers backyard, painted white. I thought it was a cool birdbath. When I got older I found out that the alcohol had been tapped out of it and drank by my Grandfather?? He had his own room in the basement where he made shine. 
I must ask Mom about that compass.


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## Derek Roger

I am informed by a good source that the bubble in a compass or spirit levels consists of Sardine Farts collected off the Island of Grand Mannan in the Bay of Fundy New Brunswick . It is apparently a very costly operation .

Given that fact Jo I doubt your Grandfather drank the contents of the compass.

Cheers Derek


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## mikeg

Derek Roger said:


> I am informed by a good source that the bubble in a compass or spirit levels consists of Sardine Farts collected off the Island of Grand Mannan in the Bay of Fundy New Brunswick . It is apparently a very costly operation .
> 
> Given that fact Jo I doubt your Grandfather drank the contents of the compass.
> 
> Cheers Derek


Bay of Fundy tide range, no wonder its costly (K)

I wonder if Jo's Grandfather has a predilection for facing north?

Cheers Mike


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## Pat McCardle

I used to start off a Monday morning with a shot of Compass alcohol chased down with neat brasso.............It never did me any harm. LoL


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## mikeg

I prefer a shot of compass alcohol sprinkled with harpic, mind you it sent me clean round the bend. LoL


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