Will compasses keep you on track? Land navigation is an essential skill to learn for wilderness survival. Therefore, the compass is a critical part of successful land navigation. People navigated by the stars, dead reckoning, and terrain association before the invention of the compass or the nautical sextant astrolabe. There are many kinds of compasses available to the modern outdoorsman. Compasses fall into two categories based on the method of needle stabilization, also known as damping: liquid-filled and magnetic induction. Thus, purchasing a quality compass for use in the field is as important as having an accurate topographic map.
1. Liquid-filled Compasses
The most common type of compass on the commercial market are those with liquid damping. Liquid damping is the method of stabilizing needle movement by immersing it in an enclosed, liquid-filled housing chamber. Several types of liquid are in use for this method. Mineral oil, kerosene, or ethyl alcohol are the most common. Minimizing needle movement in a compass ensures maintaining a direction while trekking over land. An example of a liquid-filled compass is the Suunto Clipper Wrist Compass or the Suunto M3 Baseplate Compass. A quality liquid-filled compass is an excellent option for those who enjoy the outdoors recreationally or you are living in an urban-suburban survival zone.
The advantage of a liquid-filled compass is the retail cost to the consumer. Many of the budget-friendly compasses on the market are those that have liquid damping. Commercial button and wrist compasses use the liquid dampening method for needle stabilization. Therefore, compasses manufactured with this dampening method make them accessible to the average consumer. Examples of budget-friendly compasses using liquid-filled dampening are those by Coghlan’s and Coleman.
A disadvantage of compasses with liquid damping is that the liquid can form bubbles. These bubbles can affect compass accuracy. Another problem with these kinds of compasses is that the liquid can thicken in arctic temperatures. Consequently, the thickened oil restricts needle movement. This characteristic of oil-filled compasses limits there use to non-military applications. Moreover, the high temperatures in the summer in arid environments can cause the liquid to expand or evaporate. Consequently, if the housing becomes cracked, the liquid will leak out. Thus, the compass becomes inoperable.
2. Magnetic Induction Damping Compasses
Compasses using magnetic induction damping are the second most common compasses available to the outdoorsman. A compass utilizing magnetic induction is one in which the needle is stabilized through a magnetized field created within the needle housing. The most common way that this happens is by a magnet passing through an electromagnetic field.
However, magnetic induction damping in a typical lensatic compass occurs when the magnetized needle is moving through a copper needle housing. The U.S. Army M-1950 lensatic compass is an example of this kind of compass. Magnetic induction damping compasses are the preference of most militaries around the world.
The significant advantage of a compass using magnetic induction damping over liquid damping is its use in extreme temperatures. The compass with magnetic damping is usable in extreme arctic and extreme tropical or desert environments. The absence of the liquid in the needle housing eliminates the concern over the liquid freezing or expanding due to extreme temperatures.
Another advantage of these kinds of compasses is they tend to give a more accurate and stable reading when shooting an azimuth. The stability of the needle enables their use for land navigation in both night and day situations. Most military compasses copy the lensatic sighting mirror compasses first introduced by the British on the eve of the twentieth century. You can learn more about the U.S. Army lensatic compass in my article, “A Short History of the U. S. Army M-1950 Lensatic Compass.”
A disadvantage with compasses that have magnetic induction damping is that they can be more expensive to the average consumer. The process that creates the magnetic induction damping feature of the compass is more complicated than merely filling the needle housing with liquid. Furthermore, the compass housings must be of metal construction for the magnetic damping to work. Consequently, the cost increases to manufacture these compasses.
The second disadvantage of a compass using magnetic induction damping is that it can be complicated to use. For example, complaints often heard against the U.S. Army’s lensatic compass is that it is hard to use to take an azimuth and for land navigation. By contrast, those trained and experienced with these compasses use them as well as a person favoring the Suunto MC-2 Compass. Furthermore, the U.S. Army lensatic compass was designed to meet the specific needs and standards of the military and for military operations. They were not designed for use to survive the apocalypse, SHTF, or grid-down scenarios. Therefore, it is understandable why there are complaints about lensatic compasses.
A quality compass is a must-have item in the packing lists of your various bags. The two most common types of compasses are the liquid-filled and those using magnetic induction damping. Additionally, the compass that you adopt is one that should be accurate, durable, and magnetized for the proper hemisphere. You do not want to stake your life on a compass of lower quality.
Most survival experts advise spending money on a good fixed-blade knife. The same recommendation is valid for the purchase of your compass. Furthermore, if you are a world traveler, there are quality compasses available for use in both the northern and southern hemispheres. Suunto and Brunton have compasses that meet this need. A quality compass is an instrument that will enable your survival should you get lost on the trail or the backcountry. Therefore, choose your compass wisely and deliberately.