How to Use a Compass

In the modern world, most people don’t have to think about how to get from point A to point B. The most difficult thing anybody has to do is look at a road atlas. While land navigation has become more of hobby than a skill, in the event of an apocalypse, those who do practice it would have an advantage over those who have mostly depended on GPS to get them where they’re going. Of the two basic skills that encompass land navigation, reading a compass is the more difficult but by far the more rewarding.

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In the modern world, most people don’t have to think about how to get from point A to point B.  The most difficult thing anybody has to do is look at a road atlas.  While land navigation has become more of hobby than a skill, in the event of an apocalypse, those who do practice it would have an advantage over those who have mostly depended on GPS to get them where they’re going.  Of the two basic skills that encompass land navigation, reading a compass is the more difficult but by far the more rewarding.

Basic Usage

A typical compass face

In general, using a compass is fairly simple.  Most compasses have a floating needle that always points to the north magnetic pole, but there are some (usually cheap keychain compasses) that the face is the floating piece and the needle doesn’t move. Either way, all you have to do to get your “bearing” is to point the north end of the compass in the direction you are facing and read the little number on the outside ring of the compass that the needle points to.  This is called the bearing and gives you an accurate idea of which direction you are heading in.  Most compasses are numbered from 0 to 359 (for the 360 degrees of a circle) and each right angle (0, 90, 180, 270) is a cardinal direction.  Once you’ve taken your compass bearing you need to adjust for magnetic declination (discussed next) to get your map bearing and then you can navigate yourself very accurately anywhere in the world.

If you look at the face of a compass, you’ll notice that the face appears to be backwards.  This is because the needle always faces north.  So if you turn east the needle is still pointing north, but on the face of the compass the needle is pointing at east.  When using a compass, be aware of your surroundings – metal objects and electrical objects can have an effect on your reading.  Anything from power lines (which can affect your reading from within 55m) all the way down to jewelry (which practically have to be touching the compass to affect it) can have an adverse effect on your readings.

Magnetic Declination

Magnetic declination is the term used to describe the difference between “true north” and “magnetic north”.  Where true north lies at the top of the world, the north magnetic pole lies in the Arctic Ocean just above Canada.  The north you read on a compass is actually magnetic north and because of this, you have to account for the difference between the two if you want remotely accurate readings from your compass.  There is no easy formula for figuring this out because the north magnetic pole moves.  Most topographical maps will display the magnetic declination in the legend, but in the case you only have your compass, or your map is more than a few years old, you can take a reading at night of either Polaris (the north star) if you are in the northern hemisphere, or based on the Southern Cross constellation if you are in the southern hemisphere.  Taking a bearing from the Southern Cross takes a little more effort because you have to visualize a point in the sky.  Basically, you find the Southern Cross and draw a line down the long end of the cross, then find the bright pair of stars to the left of the Southern Cross and draw a line that runs perpendicularly to them.  Now the point you want to aim at to get your bearing is the point at which your two imaginary lines meet (see picture).

How to find due South in the southern hemisphere
Picture from http://www.teara.govt.nz/en/southern-cross/2/3

The Lensatic Compass

A lensatic compass
A lensatic compass

There are a number of different types of compasses, but the compass you will want in a survival situation is a lensatic compass.  The lensatic compass was designed for use by the military.  They’re durable and incredibly accurate.  One of the most important features of the lensatic compass is that it uses a copper induction dampening system.  Where most compasses suspend the needle apparatus in a liquid in order to keep it free floating, a lensatic compass does not, so it can be used without fear of the liquid freezing or changing pressure because of temperature or elevation.  If you plan on purchasing a lensatic compass, be careful in your purchase!  Lensatic compasses are expensive, so there are a lot of imitation compasses on the market that don’t work quite right.

Center-Hold Technique

Proper center-hold technique
Proper center-hold technique

The Center-Hold technique is the most common way to hold a compass and get an accurate measurement.  This technique can be used with any compass and can be performed while walking.  It is less accurate than some other techniques but perfectly acceptable if you are only trying to go in a general direction.

To perform this technique, rest the compass on both thumbs at waist level and parallel to the ground, held between your index fingers (as pictured above).  To take a reading, just look down at your compass.  The needle will be pointing in the direction you are facing.  The reason this is ideally suited to taking readings while moving is because while you are walking you can simply glance down to see what direction you are walking in, but this will only give you a general idea.

Compass-to-Cheek Technique

Proper compass-to-cheek technique
Proper compass-to-cheek technique

If you have a lensatic compass and you need a more accurate measurement, the Compass-to-Cheek technique is a much more suitable technique.  It is far more accurate than most other sighting techniques, but it takes longer to get your reading and must be done from a stationary position.

Open the rear sight and cover of the compass to form a front/rear sight configuration.  Hold the compass level and against your cheek.  Line the rear sight up with the sighting wire in the front cover and then line the sighting wire up with the landmark you are trying to get a bearing on.  Without moving, look down through the lens to get the bearing of the landmark.

Reverse Sun Dial Technique

If you find yourself without a compass, all is not lost.  Did you know you can use your wrist watch to tell directions?  Take your watch off and orient it such that the hour hand is pointed in the direction of the sun.  Visualize a line on your watch directly between the hour hand and the twelve o’clock line.  This is the north/south line, where north is in the direction furthest away from the hour hand.  What you are doing is essentially reversing the premise under which a sun dial works.  Instead of using the suns position and a general understanding of directions to determine the time, you are using a known time and the suns position to determine a general direction.  You don’t even need an analog watch for this to work!  You just need to be able to visualize the angle at which the hour hand would be at any given time and where the 12 o’clock line would be in relation.

Alternatively, if you have time to do this, you can put a stick in the ground, mark the tip of the shadow, wait 15 minutes and mark the tip of the shadow again.  If you connect point A to point B you have created the east-west line.  West is always in the direction of point B to point A (the direction the sun is moving).

Further Reading

Author: Adrian

Adrian Hannah is a system administrator and poor college student at Michigan Technological University. He currently resides in Hancock, MI where he observes the outside world and puts in his two cents.