What is a Liquid Compass?

Mary McMahon
Mary McMahon

A liquid compass is a compass which is filled with fluid. The fluid acts as a buffer, absorbing shock and vibrations to avoid damage to the elements in the liquid compass, and it also helps to stabilize the compass needle to make the device easier to read. Many compasses are liquid filled, and they come in a variety of styles ranging from ball compasses to small models which are designed to clip onto a keychain so that they are available for easy reference.

Hikers often use a liquid compass.
Hikers often use a liquid compass.

The concept of the liquid compass was introduced as early as the 1600s, but did not catch on until the 1900s, when they were adopted as standard navigational instruments by several navies. The compass includes a needle which is sensitized so that it will always point towards Earth's magnetic north, with a backing which is marked with degrees so that users can determine which direction they are facing on the basis of the marking the needle lands on. Using a liquid compass, people can determine which direction they are heading in, and use this information in navigation.

The viscosity of the fluid can depend on the design; alcohol, oil, and kerosene are three common choices for fluid, and it may be dyed to increase visibility. The compass is designed to allow the liquid to expand and contract slightly without breakage. One advantage to using a liquid compass is that the needle stabilizes very quickly and prevents wobbling, allowing people to take accurate measurements more easily. Another is that the device tends to be more tolerant of shaking, dropping, and other forms of abuse.

Numerous companies make liquid compasses of all shapes and sizes. The liquid damped compass continues to be a handy basic navigation tool, although it has been largely supplanted by things like GPS devices. A compass will still work when GPS is broken or unavailable, however, and many people learn the basics of compass navigation as part of their training for hiking, boating, and other outdoor activities, during which being able to navigate can be very important.

One important thing to be aware of when someone uses a compass is that the device points towards magnetic north, not true north. Magnetic north actually wobbles around the geographic north, making it necessary to adjust for declination, the variance between magnetic and true north. Many compasses allow users to adjust for this, and declination information is usually published on maps and charts.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a EasyTechJunkie researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments


Bayol 35 is used as liquid in marine magnetic compass.

ethyl alcohol :water = 2:1


Hey everyone. I have a trick for finding leaks in a liquid compass. My compass had an air bubble in it, so I assumed it had a leak. I couldn’t find the leak, though, so I went on the internet and found this trick.

First, buy some fluid from your compass’ manufacturer, and sit the compass and the bottle of fluid in the refrigerator overnight. The next day, open your compass and fill it completely. Securely close the compass, then wipe off the condensation and sit it on a paper towel in a warm room for a couple of days.

After a few days, you should find the leak! Then all you have to do is change the broken component.

I think this will only work if you get the exact same fluid your compass already has in it. It’s not good to mix different fluids, anyway, because that can damage the compass


@qwertyq – I have the answer! I’m a seasoned hiker and I know a little about this. Oddly enough, liquid compasses used to be filled with kerosene. I think that’s a strange choice, since it’s flammable, but I guess they needed something that wouldn’t freeze in snowy areas. Later, some compasses were filled with pure ethyl alcohol, which also doesn’t freeze as quickly as water would.

These days, most liquid compass fluid is made of silicone. It’s very clear, not flammable, and doesn’t freeze in wintery conditions, so it’s perfect for the task.


So, what type of fluid is usually inside a liquid filled compass? My first guess would be water, but I don’t know much about lubricants or different fluids. Does anyone have the answer?

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