Join Date: Feb 2008
Location: N. VA
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Change the Compass Oil
If your compass is small (e.g. 3") you may simply want to replace it since smaller compasses are not that expensive and repairing compasses yourself is aggravating. But if it is larger (and therefore more expensive) and it only suffers from cloudy oil, you may be able to drain and change it. Your compass may have a plug in the bottom you can remove to drain and refill it. The trick is making sure to use the right liquid. The problem is that without knowing the manufacturer, it's hard to tell what the right liquid is, and you didn't say who made it.
In the old days, magnetic compasses used to be called Whiskey Compasses because the fluid was high-proof alcohol. If you think your compass fluid is lighter weight stuff like alcohol instead of the heavier light oil, then my experience applies.
When I bought my '84 Islander last year the compass (a 5" Danforth Constellation) had a badly scratched dome, cloudy oil, and a huge bubble. The Danforth has a port where you can add compass oil, so over the Winter I took mine apart, cleaned everything, put on a new dome and o-ring, and then filled it with new compass oil. It took a couple of tries to get it sealed so it didn't develop another bubble, but it looks great now.
Some folks advocate filling a whiskey compass with Mineral spirits instead of an alcohol-based compass oil because it is so much cheaper. While the viscosity is similar, mineral spirits will eventually darken and become cloudy due to interaction with parts inside the compass and sunlight.
I ended up filling my Danforth with Ritchie compass oil. So far, so good!
Good luck with your project.
T. P. Donnelly
S/V Tranquility Base
1984 Islander 30 Bahama
Last edited by dacap06; 07-20-2009 at 01:32 PM.