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DaveOnCudjoe · 08-10-2009, 15:03

My bulkhead mount compass has lost it's oil but has a plug in the top that I assume is for refilling or topping off. 2 questions, is it common to need to refill the unit and if so what oil is appropriate? Thanks in advance, Dave

**jackdale** · 08-10-2009, 15:10

Leaking is probably symptomatic of a problem.

Many compasses use mineral spirits, but check with the manufacturer to determine what to use.

Jack

**Solitude** · 08-10-2009, 15:11

I believe its mineral oil.
I'm sure you could call a compass supplier and get the right oil for your compass. It would be a bummer if you mixed the two and have some kind of adverse reaction.

Disolving paint or something.

**hellosailor** · 08-10-2009, 17:49

Dave, if you use the wrong fluid you'll fubar the compass, so checking with the maker is not optional. SOME of them will also offer you a repair/exchange at a killer price, so ask about that at the same time.

Fluid doesn't just go away--you've got a leak and unless you fix it, you'll just be buying more fluid, regularly.

hanschristian38 · 08-10-2009, 17:54

If it is a Ritche, you should be able to get the fluid at West Marine. When I worked there, we stocked it.

**thinwater** · 08-10-2009, 18:14

As others have pointed out, there is a problem. The most common is the rubber diaphragm that allows for expansion is cracked. It is probably located on the bottom of the compass. The manufacturer typically sells them for ~ $15. Generally easy to replace.

The fluid is generally a thin mineral oil, but it varies with the compass. Match the viscosity of what comes out - something between very pure lamp oil, baby oil, but generally not mineral oil; it is too thick.

To get the last bubble out, burp it by pressing very lightly on the diaphragm while screwing in the plug.

Be gentle, and good luck.

**GordMay** · 09-10-2009, 06:29

Check with the manufacturer.

Until recently, most compasses used Odorless Mineral Spirits as their damping fluid.
Ritchie (for one) now uses a fluid called Isopar L ® (*1) that has similar properties, but with some added benefits over Odorless Mineral Spirits. The two can be mixed together.
(*1) Isopar L® is a Registered Trademark of Exxon Mobil Corporation - generically known as: Isoparaffinic hydrocarbons (Isoparaffin), Hydroheated heavy naphtha (petroleum).

Some older style (up to 1960's) Compasses used an Isopropyl Alcohol and water mix, or Kerosene.