What is the fluid in floating compasses ?

[S/V Illusion]

Originally Posted by a64pilot

Before I removed it, I would index it, maybe something as simple as a pencil line so you could put it back exactly like it was

Does that change where north is?

Also, it's futile adding fluid unless you first fix the cause of the leak.

[Scaramanga F25]

SORRY.

Air under diaphragm contracts.

Works for me.

[C.Karo]

Its called VARSOL... I WIN!!!

[socaldmax]

Originally Posted by NSpence

FYI Scaramanga F25 Fluids do NOT contract or expand.

Yes, they do. That's why there is a diaphragm on compasses. It's called coefficient of expansion, and it's been measured for every fluid. That's also why water temp. is extremely important for subs to measure, since the buoyancy and trim of the sub is dependent on the current water density, dictated by salinity and temperature.

As a matter of fact, the US oil industry has been caught heating diesel fuel to decrease how much fuel you get, since the pump measures volume, not weight. They've calculated that nationwide in the US, since all of the pumps are calibrated at 231 cubic inches @ 60*F, the diesel fuel pumped into your car @100*F (very common, and highly suspicious since underground tanks shouldn't be anywhere near 100*F) robs you of 1.84% of the fuel you paid for, and when you're talking billions of gallons, this adds up to millions in extra profits.

[Cheechako]

Mineral oil.

[dick sargent]

On advice of repair pro I successfully used cigarette lighter fluid

[a64pilot]

Originally Posted by S/V Illusion

Does that change where north is?

Also, it's futile adding fluid unless you first fix the cause of the leak.

Sometimes the mount will be slotted so a few degrees of adjustment can be made, you find this out of course when you swing the compass, if you card says always add three degrees to your steer, then of course your compass should be adjusted to the left three degrees.

[hellosailor]

A compass is filled with "compass fluid" which can be any one of a dozen chemicals. Mineral oil, naphtha (lighter fluid), alcohol, kerosene, a couple of more along wwith various blends designed to change teh viscosity and dmpen the movement.


The "ink" on the card may melt off if you use the wrong fluid. Any if the housing is plexi, petrochemicals may cause it to yellow then craze. If the seals are rubber, the wrong fluid will eat the seals and it will leak again, assuming you have changed the seals since it must be leaking if there's already a bubble in it.


Best bet is to call the maker, use what they say (unless if it cheaper to toss the compass) or use a real repair shop like Robt. White up in Boston (if they're still there) who will know what to top it off with.


Done properly you'll get 25 more years. Done at random, six months.

[NevisDog]

Originally Posted by NSpence

FYI Scaramanga F25 Fluids do NOT contract or expand.

Hold on there - if fluids don't expand or contract then how come the alcohol in a thermometer climbs up the scale as temperature rises?? C'mon guys, pull the other one.
(BTW I'm new to this forum and grateful for all the useful information found here.)

[gbohner]

Iwas told and I have used glycerin, which you can get in a drug store.

[model 10]

Originally Posted by a64pilot

Sometimes the mount will be slotted so a few degrees of adjustment can be made, you find this out of course when you swing the compass, if you card says always add three degrees to your steer, then of course your compass should be adjusted to the left three degrees.

If you did that for say north, it would be off going south too Same for east and west. A good compass will have small magnets inside that you can adjust so you average out the error between north and south and between east and west. Then you can make a correction card, If you need one. If you can sail a course within just a couple of degrees, you are amazing.

[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.

[df1995]

Originally Posted by Scaramanga F25

I have used and would use proper compass fluid.
You may need a syringe or an eye dropper.
Do not over tighten filler screw nor drop O ring.

Depending on the state you are in it may be difficult to obtain a syringe. New York, for example, requires a prescription. In permissive states the easiest place to buy one is in an animal feed store.

In New York City, I would just ask a junkie around Union Square.

[NevisDog]

Originally Posted by Guy

If you did that for say north, it would be off going south too Same for east and west. A good compass will have small magnets inside that you can adjust so you average out the error between north and south and between east and west. Then you can make a correction card, If you need one. If you can sail a course within just a couple of degrees, you are amazing.

I think you missed the point here. When reinstalling the compass, if the compass lubber line is not reset exactly in line with the ship's centerline then the same error will appear on every heading. No one wants to sail with a three degree compass error on every course.

[Mojadito]

FYI NSpence, fluid most certainly does expand and contract. Says the guy who filled up the gas tank, early on a day when it got very hot!