compass

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I have an old 'Fleetwood' magnetic compass which had a little accident.
It has a brass cylindrical casing and both the upper and lower discs are glass so that the compass disc can be viewed from the wheel house or from the saloon.
Presumably this compass originally came from a large yacht or maybe from a trawler.
One of the glass faces was cracked and I have replace both discs.
I would be glad to hear if anybody knows exactly what is the best type of alcohol/solvent to re-charge the compass with.
I tried clear ethylene glycol but the disc floated in the casing instead of sitting down on the needle. The glycol SG was probably too high.
 
Michael,

Best drink the jin but not after its been in the compass.

I was asked probably ten years ago now, to test a sample of compass fluid to identify it. Infra red analysis identified it and as far as I can remember it was Linseed Oil, which must be ultra pure otherwise it will soon go yellow with oxidation of the impurites by sunlight. But I am not 100% sure after 10 yrs as they say perhaps ask the audience. Would be very interested to know if Im right.

Trevor
 
The manual that came with my compass specifies a mixture of one part ethylene glycol to two parts distilled water
 
Michael,
Tried to find out some more info, some maufacturers refer to compass oil others to compass fluid not very helpful. It looks as though there is not a definitive answer to your question not all compasses will contain the same liquid.

So the best bet would if possible find whats used in your specific compass, obviously the maufacturer would have this info. You should be able to lever the information from them for Health & Safety reasons they should supply it.

The correct liquid is important as you have found out the following factors should be considered :

(1) The liquid should be non-toxic.
(2) The liquid should have a low freezing point.
(3) The liquid must be of the correct viscosity (for the compass).
(4) The liquid must have the correct density.
(5) The liquid must not affect the plastic or compass card.
(6) The liquid must be relatively cheap and easily available.
(7) the liquid must not be flammable.

Evidently most modern compasses use a mixture of alcohol and distilled water.
The literature did not say which alcohol. If your liquid smells alcoholic I would find out its density and then mix IMS industrial methylated spirit (Ethanol) with distilled water to the same density. The density of ethanol is 0.789 gm/cc @ 20 centigrade.
The IMS is 95% ethanol / 5% water and does not pass my criteria (7) but when mixed with more water should reduce its flash point making it as safe as the Gin.

If your compass fluid is oily then the supplier would be your only hope.

Hope this has you pointing in the right direction.

Trevor.
 
Trevor,
Many thanks for your help with this.
The liquid was lost when the glass cracked but it seemed to smell more of methanol than ethanol (sweet).
One of the respondants suggested that I contact a compass specialist in Hull. I'll do this and I'll let you know the outcome. I know that it is a 'Fleetwood' compass and I have the type number so I am hopefull!
Michael.
 
Re: compass/methanol

Yes it is possible that they used methanol as the compass is old. Wouldn't be allowed to use it nowdays with all the health & safety concerns with methanol.

Look forward to hearing how you get on.

All the best.
Trevor.
 
Michael

I asked this question on this forum 2 years ago. I got all sorts on anecdotes about Arabs stopping Navy Ships and begging Compass Fluid (alcohol) which they subsequently imbibed with glee. The very best advice seemed to be to use White Spirit which I did and it has worked very well for 2 seasons. Go for it with the White Spirits

Martin
 
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