As a navigation aid, the two basic uses of the magnetic compass is to allow the user to determine the azimuth or direction in magnetic degrees of a desired diration, and to set a direction again in magnetic degrees on the compass using a rotating bezel and follow that azimuth (dead reckoning).
Compasses are an essential tool for the Urban Survivalist to have, even if you think you can make it from your urban location to your designated safe location via a wheeled vehicle without ever having to walk cross country. Knowing the basic uses for a compass are just common survival skills, like tying knots, building a fire or shelter, etc.
The magnetic compass has a magnetized NORTH seeking arrow which depicts magnetic NORTH as opposed to Grid NORTH which is what maps are oriented to.
One of the better compass to have is the military Lensatic Compass with Tritium Luminous index marks and luminous NORTH seeking arrow for use at night.
Parts of the Lensatic Compass.
Determining (Shooting) Azimuths.
1. Bend the rear sight with the sighting slot to a 45 degree angle over the floating dial.
2. Flip up the compass cover 90 degrees so you can look through the sighting slot and through the sighting wire on the compass cover. Just below the sighting slot is a magnifying glass that you look through to read the degrees on the floating dial.
3. As you sight on an object through the rear sight, center the sighting wire on that object. Holding the compass steady and level, look down, through the magnifying glass, at the floating dial and read the azimuth aligned with the fixed black index line. This is the magnetic azimuth from you to the object.
Setting an azimuth on the Lensatic Compass.
1. Keeping the compass level, rotate the compass until the black index line is on the desired azimuth. Then rotate the bezel ring until the short luminous line on the bezel ring is matched up with the luminous magnetic arrow.
2. You can move with the compass open keeping the short luminous line on the bezel ring matched up with the luminous magnetic arrow and you will be on the selected azimuth – this is called dead reckoning.
The Civilian Silva Style Compass. The use of the Silva style compass is very similar, rotating the bezel ring to line up a mark on the bezel with the NORTH seeking arrow. The disadvantage of the Silva style compass is that determining more precise azimuths from you to a distant object with harder without a sighting slot and sighting wire. However these are excellent compasses and cheaper than the Military Lensatic Compasses. Our motto is "One is none, Two is one" - meaning have a backup, so having one of each is not a bad idea for the well equipped survivialist. Silva Style Compass shown below:
Walking on short legs on a compass azimuth it is very prudent to keep track of the distance you have traveled and to match terrain that is depicted on the map to what you are seeing on the ground – this is called terrain association. You need to be able to determine what the terrain features are and how they should look in 3D. Using dead reckoning and terrain association together is your best chance of navigation through unknown country and is, again, a basic skills for Urban Survivalist as you never know when circumstances, vehicle failure, lack of fuel, criminal threats or the weather and environment will force you to move over land cross country.