Most every survival kit has at least one compass in it. Why? It is not one of the ten most important things which SHOULD be in a kit. It is probably there because people think it should be there, and because they can be small and cheap. Of course, a compass actually does have two important uses so generally would make the top 20 list. I’m going to suggest you don’t have one IN your kit; but you should indeed have one WITH your kit.
Let’s face it, the best survival use of a compass is to prevent you from getting lost and thus needing your survival kit. But a compass can not do its job if it is packed away in your backpack, your belt pouch or even in a container in your pocket. Although of less use ‘in the city’, as soon as you are ‘in the wild’, your compass should be out where you can easily refer to it. And the best place for that is on your wrist. There you can often refer to it to make sure you are on the right path, it can’t get dropped or lost, and you don’t even need to let loose of anything you are holding in either hand to use it. Hanging around your neck or on a tether would be an acceptable alternative; you can slip it into a pocket to keep it from flopping around or getting snagged and use the lanyard or tether to pull it out for use. Another option would be to fasten it to your clothing or equipment.
Once you are in a survival situation, in many cases, staying put is your best bet, which means the compass has no further useful function. But if you need to move, then the value of a compass skyrockets. If you know for a fact that where you need to go is ‘somewhere South West of here’, then the compass can help you to go that direction. Conversely if you need to vacate where you are because it is unsafe or does not have needed resources, the compass can not only ensure you move in a straight line rather than wander around in circles, but can allow you to leave a note with your intended direction at the scene of a crashed plane or disabled vehicle or other likely to be found site. Or if you need to leave a site and be sure to be able to return, the compass can be used to accurately track your path to facilitate retracing that path or computing a return course. If you have an accurate map of the area, the compass will allow you to determine where you are and where you need to go to get help or resources, and help you get there.
So having a compass is worthwhile, but which one? For something so simple in concept, there are a wide variety of choices to make. The first decision is the type. The smallest (self-contained, ready to use) option is the ‘button compass’, which is ‘nothing but compass’. Available in a variety of diameters, the only advantage of these is the small size (and usually price). The small size makes them a bit difficult to use, and very easy to drop or lose. They do not have a hole to attach a lanyard to in order to reduce these problems, but many have a groove around them, which you could tightly wrap with wire (non-magnetic of course, such as brass or stainless steel) or very strong string (such as Kevlar), and attach a lanyard that way. If this is your compass type of choice, get the biggest diameter suitable for your circumstances.
Next is the ‘built in’ compass. This type has the compass as part of something else, such as a whistle or flashlight or knife or matchbox. This is a useful concept, but be sure that whatever the compass is part of is adequate in its own right. Many of these combinations are junky toys, not reliable survival gear, so should be avoided.
Often a superior choice is an ‘attached’ compass. This is, a compass which is attached, or part of something attached, to you. Most common and often optimal, is a wrist compass or a watchband compass. The latter can be built into the watchband, or more commonly slide onto it or clip to it. This class also includes ‘pin-on’, ‘zipper pull’, and carabiner compasses attached to your clothing or pack.
The ‘king’ of compasses is the ‘lensatic’ compass. These have the precision and mechanics to take very accurate bearings of objects near and far. They are invaluable if you need to follow a specific course or determine the exact heading of an object, but are almost never are fully utilized in a survival situation, so generally are not the worth the size, weight and cost.
Electronic compasses should be avoided, as they tend to be bigger and heavier than ‘low tech’ compasses, and require batteries which can discharge or leak in storage, or become depleted in use. Plus, electronic devices have been known to fail on occasion, with or without a discernible cause.
The final common option is the ‘baseplate’ compass. This is a compass mounted on a clear plate with scaled markings on it. These are of great use along with a map, but if you don’t have a map may not be worth the extra space they take. Although the plate does make them easy to hold during use. An interesting variation of this is the ‘covered’ version, which has a cover which flips over the compass part for protection. Usually these covers have a mirror and sight line inside them, which not only can provide some of the function of the lensatic compass, but can be used for signalling as well.
Once you decide on the type, you need to worry about the ‘zone’. What, you did not realize that most compasses are optimized for a particular part of the globe? Don’t feel bad, most people don’t and neither did I until I did the research. As you might imagine, in order to provide an accurate reading, the needle must be balanced so as to not drag on the bottom or top of the capsule. The optimal balance point varies depending where on the globe, from top to bottom, you are located, so most compasses are optimized for one of five bands around the Earth. Zone 1 is the northern part of the globe including North America and much of Europe and Asia. Zone 5 is the southern part of the globe including only Australia and New Zealand. Sunnto has invented a ‘global’ needle technology which will work the same anywhere on the globe, but unless you are on a continent with several zones (particularly South America or Africa, each with three zones), it may not be worth the extra cost and limited selection of models.
Most people do realize that compasses do not point to ‘geographic’ North, but rather to ‘magnetic’ North, and this difference is known as ‘declination’. Some compasses have built in declination adjustment, but you still need to know what the declination is for where you are in order to set the adjustment. Oh, and declination changes over time. Fortunately, declination is not a factor in most survival compass usage.
To be, or not to be, liquid filled, that is the question. The purpose of the liquid filling (usually an oil) is to dampen the needle, which reduces the time it needs to settle and reduces oscillations for more accurate reading. The only downside is the potential for leakage; not a major concern if the compass is quality. Often these develop a small bubble over time, but as long as the bubble is small and stable in size, this is probably not a critical concern. The dampening is often quite useful, so before settling on a non-dampened compass, try it out to make sure that it is neither too slow to settle or too ‘quavery’ for you.
The last decision is illumination. Compasses can have Tritium markings which continuously glow in the dark (for 10 years or so before wearing out), phosphorescent markings which glow in the dark for a while after being exposed to light, or no night markings. Tritium is the best, but may not be worth the extra cost and limited life span. Phosphorescent compasses are common and usually adequate, particularly if your kit includes a source of light to ‘charge’ it with. No illumination at all should be avoided, as it makes the compass difficult to use in the dark.
Top manufacturers include Sunnto (Finland), Silva/Nexus (Sweden) and Brunton (US), but some other companies make ones which would be acceptable.
Here are some wristband compasses. From top to bottom is the Cammenga Tritium, Techna diving, an unmarked compass from Sweden, and a watchband with clip on compass (left) and a slip on compass with a matching thermometer. The ‘best’ survival compass, in my opinion, is the Cammenga, which is rugged in addition to being self illuminated. It does not appear to be liquid filled but settles quickly and with good stability. It claims to be military issue. For non-Tritium illumination, the Techna is (or was) a good choice; the whole disk glows, not just the needle and a few marks like most others, plus the spring loaded buckle makes it the most comfortable. It is discontinued, of course.
Here are a couple of covered baseplate models by Silva, and a large Brunton ‘zipper pull’ model with a built in thermometer. Note that the smaller Silva has a safety pin in the hinge area, which allows this to be pinned to your shirt or jacket, a useful option, although with an opaque baseplate it is not fully usable with a map. The bigger one is probably only suitable for bigger kits or if used with maps.
Here are a couple of button compasses of various sizes, shown next to a quarter for scale.
Finally, here is a carabiner compass with matching thermometer and a nice small zipper pull compass.