Compass & Map Navigation
The reliable, traditional way to get around...
Magnetic fields surround the earth & come together to form the magnetic north & south poles. A magnetized needle will rotate and align itself with these magnetic fields. When a compass is held level, the red (typically) end of the needle will point towards magnetic North.
As you face North, imagine a circle marked 0o to 360o surrounding you, with 90o marking East, 180o marking South, 270o marking West, and 360o (or 0o) marking North. Any one of those 360 degrees or numbers is a direction or "bearing" from North. The compass azimuth ring represents that imaginary circle with all the degrees printed on it. Rotating the azimuth ring to align it with the needle provides you with the bearing from North to the direction of travel or a landmark.
What is Declination?
Declination is the angle difference between True North (ie. the globe's North Pole), and Magnetic North. Declination is different depending on your local position on the globe. Since all maps are geographic representations, they use the physical North Pole, while compasses are bound to the Magnetic North. Therefore, compasses must be adjusted to the appropriate declination angle for the area you are travelling in (usually indicated in the legend of your map).
Declination-adjustable compasses have a declination scale printed on the azimuth ring, or may have a method of creating an offset that makes it easier to take bearings.
Choosing a compass...
There are many different compass styles & features available to suit a variety of applications.
Fixed Azimuth Ring
These compasses are the simple ones that have no moving parts - just a needle that spins to point north. Such compasses are excellent for general direction finding & are great for kids, travelers, skiers, & anyone needing a quick reference point.
Base Plate Sighting
These are usually transparent base plate style map compasses. Backpackers, hikers, campers, hunters, & adventure racers generally use this type of compass. The advantages over fixed azimuth compasses include increased accuracy, declination adjustability, & ease of use with maps.
Mirrored Sighting
This style of compass is designed for meeting the demands of more advanced users. Expedition members, outdoor skills instructors & surveyors all require the precision that this type of compass affords. Its advantages over the other systems is that the sighting mechanism allows you to simultaneously align the needle while viewing the object you are taking a bearing to. Accuracy can be up to 1 degree on some models.
Whichever compass model you choose, it is a good idea to practice map & compass skills. Proper planning for your trip takes very little time, but can make the trip far more rewarding.
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