2. Does anybody know the liquid that usually fills up compasses, depth gauges, and SPGs? I've heard somebody say it was kerosene, but i wanted to make sure. I'm trying to repair a compass and i need more liquid to fill it up.
The compass probably had glycerin, refined mineral spirits, or perhaps alcohol in it, from what I've read. See links below.
I successfully eliminated a 1/2" wide bubble from a scuba compass a few years back. FWIW, here's how I did it.
After getting the module out of its housing, I used a 0.050" drill to create a tiny hole in the area of the original fill port, being careful near the bottom of hole to avoid punching through completely, so as to reduce the chance of introducing debris. Prior to breaking through, applying some slight squeeze to the compass case with a C-clamp on the top and bottom insured that escaping fluid would eject any debris and also provide a tell-tale when entry was achieved. You don't need to complete the drilling past initial breakthrough.
I might try a hot needle next time. Might be simpler and cleaner.
The fluid inside the compass was quite a bit thinner than mineral oil. Thanks to being a packrat, I had a broken Ritchie boat compass laying around and I drained its fluid to use in the scuba compass. The fluids of the two compasses were similarly thin, although the Ritchie had a slight petroleum odor, very much like mineral spirits.
For refilling, I had poor results using a fine-gauge needle and syringe to try to add fluid and withdraw air bubbles, as the bubbles tended to adhere and separate maddeningly.....
Getting a little smarter, I then tried placing the compass in a bath of compass oil to "bleed" the unit. I minimized the amount of oil needed by wrapping the compass in a close-fitting thin-walled plastic bag, like those from the produce section of grocery store. Then I added enough oil so the fill hole would stay covered through the bleeding process.
With the fill port held highest, alternately pressing and releasing the top and bottom of the compass ejected air and sucked in oil. The bubble was replaced with oil in just a few pump cycles.
After the compass was bled and filled, I applied a slight squeeze with the C-clamp and wiped up the resultant overflow of oil from the fill hole and surrounding area, followed by using alcohol to clean the oil off as well as possible. Using a soldering iron, I melted the surrounding plastic and made an initial plug of the fill port, releasing the C-clamp to draw in the molten plastic.
Now, with the unit depressurized and plugged, I thoroughly cleaned the area around the port with alcohol and, after it was dry, finished melting nearby plastic to improve the plug of the hole.
The repair worked very well.
Some product websites and discussions of refilling compasses follow.
Here's a website selling refined low-viscosity mineral spirits as compass oil:
Ritchie - Compass Oil, Low Viscosity
Here's West Marine's offering of Ritchie I Navigation Fluid:
West Marine: Fluid for Ritchie Compasses Product Display
The description:
If you ever need to refill or top off the fluid in your Ritchie compass, the manufacturer recommends Isopar L, an odorless, colorless, refined synthetic fluid. Its low viscosity promotes quick swinging. Won't freeze or boil off at temperatures from -40º to 200º F., and it may be mixed with the mineral oil already in compasses made before 2001.
Discussions:
Compass Oil - Cruisers & Sailing Forums
Compass Fluid - Moderated Discussion Areas
Liquid Inside Compass
Good luck!
Dave C
