What is the fluid in floating compasses ?

[NevisDog]

Don't be too hard on NSpence, what he meant to say I'm sure is that fluids cannot be compressed - a simple mistake.

[B25Matt]

A large air bubble, as you indicated in your post, means there's a leak somewhere. There's no point filling it until you fix it.

I replaced all the seals on my older Ritchie compass a couple of years ago to great effect. The large diaphragm had gotten old and cracked and wasn't holding any fluid. This year the dome has gone and I'm in the process of ordering a new one.

I used petroleum based lamp oil. I first tried glycerine but it was way too viscous. Acrylic doesn't like alcohol and will cause cracks over time.

Matt


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[44'cruisingcat]

Originally Posted by cowboy58

i had same thing happen when I didn't remove mine for the winter i took it off and brought it into the house and allowed it to warm up the bubble went away.

How does this happen? It happens with one of my compasses too. It gets an air bubble at times, but at other times it's gone!

I can't understand how the air is getting out, or where it could be going?

[four winds]

It has no air in it. It's a vacuum.

Years ago I removed my compass to service the control cables. Started removing the wrong screws and lost some compass fluid. A one inch diameter bubble was in the top of the globe.

Thought I was going to learn something about compass fluid and filling. But the next day the bubble was gone, never to return. Now I realize the diaphram had something to do with this.

[44'cruisingcat]

A vacuum? That's kind of hard to believe. Wouldn't the fluid boil? I can't see the compass housing standing up to atmospheric pressure.


How did the vacuum get in there? It wasn't there when the compass was new....

[four winds]

Could very well be I am wrong.

That's my conclusion after losing fluid in the compass. I assumed the diaphram compensated over the next few hours.

I guess I figured if it was air, where did it go. And if it was a vacuum it could appear and disappear because nothing was actually there.

[Nicholson58]

Originally Posted by Idle

A large air bubble appeared in my Horizon Compass. I did not take it out yet but I presume it must have a filling hole. To avoid rusting and weed formation under the sun what kind of a fluid is added?
Idle

You can re-fill yourself if you can be certain you have the right fluid. I ruined a hand-held puck using what was 'supposed to be right' All of the numbers flaoted off the card.

When we got the current boat it was empty. With the past disaster, I took it to a compass repair service. It was vacuum refilled; calibrated; new light installed and a new card. W&P Venus. The filling port cover had disintegrated from age. W&P would have charged a fortune.

COMPASS REPAIR
Superior Instrument Service $175:00
1611 N. Airport Road
Waterford, MI 48327
Tel. 248-666-3450

AOPA Airports: Superior Instrument Svc, Inc. at KPTK

These guys are at the airport & they repair avionics.