The usual fluid inside a compass is a type of thin oil which has a low freezing point. This is not always readily available unless you have contact with a professional compass repair facility. I have used methyl alcohol (methanol, methyl hydrate) in my compasses for many years. It has a low freezing point and provides good dampening qualities for the card.
09-25-2001 04:00 PM
The fluid inside is mineral water. You can buy it at and marine store. Inside the compass underneath is a rubber seal that allows the fluid to expand when it''s warm. If it''s an old compass the rubber seal may be cracked. Or it can be loose. If it''s cracked you''ll need to get another.
09-24-2001 06:19 PM
The yacht I crew on has a mounted compass which has lost all its internal fluid. There''s no obvious hole. What is the fluid, and how can it be replaced?