by Kevin W Byrom

Created on: July 24, 2011   Last Updated: July 29, 2011

In the hands of a trained individual, a compass becomes an invaluable tool to the one who wields it. Whether it's used to plot a path from point A to point B, determine what quadrant you're located in, or locate your approximate position on a typographical map when you aren't sure where you are, the importance of having and knowing how to use a compass will never be overshadowed by the technological marvels of global positioning satellite (GPS) devices when the technology fails.

What is a compass?

A compass is a simple device which contains "a magnetized metal needle that floats on a pivot point." This needle always points to the northern magnetic field of the earth. It's important for you to remember this critical point because the magnetic field of the earth is constantly changing, so any time you need to use a compass, you're going to have to account for a difference between the compasses (magnetic) north, and the true (polar) north. This difference is known as the declination variance.

All typographical maps that are commonly used with a compass out in the wild are imprinted with the declination variance when the map is made. To be sure that you have the most current declination variance for any area you plan to traverse with a compass, you can contact the National Geophysical Data Center (NGDC) for the information.

Due to subtle differences in various compass designs, a mountaineer's compass is used as the basis for these instructions.

The first compass bearing you need to learn is how to get from point A to point B.

1. Mark your starting location on your typographical map, and then place a mark at your destination. Using a ruler or other straight edge, draw a straight line from your starting point to your destination.

2. Place your compass on the map so that the center of it is directly over, and in-line with your line between points A and B.

3. Rotate the dial on the compass housing so that the large red arrow points to the north on your map, and the smaller lines within the housing are parallel to the map's grid lines that point north.

4. Take a look at the mark on your dial that's in-line with your direction of travel. This is your relative directional bearing.

5. The next thing you need to do is to take the magnetic declination variance and adjust your bearing accordingly.

6. On your typographical map you'll find a small diagram with the letters "MN" for magnetic north listed on it, and just below the "MN" will be an arrow and a number. This number is the magnetic declination variance

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