Most people making or using maps would feel lost without a compass. Map and compass skills are easy to learn, and there are many references available.

Books on GPS spend whole chapters explaining what to do if your batteries run down, your map blows away, or you're lost with no one but a friendly pack of wolves to guide you. The message, of course, is to never depend on one method of navigation.

A mirrored or sighting compass can improve accuracy. Also, the compass must be far away from iron or steel objects: A few feet to a meter away from small objects like a flashlight or pocketknife, 20 to 50 meters (or yards) from larger objects like cars, buildings, or powerlines.

You can use a GPS receiver to find direction, but a compass is usually easier and more accurate. If you're not moving at least 10 miles per hour, a GPS receiver may show your direction of travel incorrectly.

Puffin Point

Magnetic Declination

Magnetic North usually isn't the same as True North because Earth's magnetic poles are hundreds of miles from the "true" North and South poles. A correction angle called "Magnetic Declination" is often shown on a map. Declination varies from place to place, and slowly over time.

You'll need to adjust a compass reading by several degrees to get a True bearing from a Magnetic bearing, or vice versa.

Some compasses have built-in correction scales for declination, and most GPS receivers can show your direction of travel as "magnetic" to help you match GPS and compass readings.

Puff Ball

Map and Compass

Practice with a map and compass will help improve your GPS skills, and could be very useful someday. Get a map of somewhere near home, orient the map to your surroundings, then measure the direction to various mapped landmarks or GPS waypoints.

If you set your GPS receiver to read bearings as "Magnetic", the direction to known waypoints should read the same as the compass. Compare the accuracy of your GPS and map/compass measurements.



You can make your own maps using just a compass and some way of measuring distance. You can also use a hand-drawn map to supplement your GPS readings.

An uncorrected gpsMap of a complex trail intersection may be distorted by GPS errors. A little do-it-yourself mapping will improve your results.

To use a drawn map to supplement GPS readings, be sure to show Magnetic or True North, some sense of scale, and a common reference point or coordinate grid. Our GPS accuracy section has more ways to improve accuracy.

NEXT: U.S. Geological Survey, Maps

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