Most people carry a compass and a map when backpacking. Other than knowing that the trail shows where the trail goes, and the compass tells you which way is north, most give little thought to how to use the two together. In this lesson we will discuss the different types of equipment you will need, what their uses are, and what variations exist for you to get.
A Map is a 2 dimensional representation of a portion of the earths surface drawn to scale as seen from above. There are different types of maps like topographic maps, photo maps, and strip maps.
The most common of the maps hikers use are topographic maps, which shows topographic features using continuous lines to represent similar elevation features.
The most important features you need to note right away on a map are Scale, and declination.
Scale is the ratio of map to earth. A common map scale is 1:50,000. This means 1" of map = 50,000" of earth. Scale is important because the higher the scale, the less detail on the map; and the lower the scale, the more detail on the map.
Declination is the difference between grid north, magnetic north, and true north. The most important is grid to magnetic declination. Because the earth is round, and maps are flat, there exists a slight difference between what your compass will say north is, and what your map will say it is. Not all maps have declination, but it is very important to find out if your map does!
A compass is a device that uses a lodestone (magnet) to align its dial or needle along the earths magnetic axis. Compasses come in different models, but basically there are three: Standard, Lensatic, and button.
Standard compass. This compass is the normal flat compass that most people carry. Some have flip up mirrors or built in magnifiers, but basically they al work the same.
Lensatic compass. This is the standard military compass. This compass is characterized by a flip up cover with sighting wire, and a flip up magnifying lens with sighting notch. It the most accurate compass.
Button compass. This compass is usually only used to determine general directions. They come in a variety of devices like fire starters, knife pommels, watch bands, safety pins, etc. They can be useful for determining general direction or emergencies, but for accurate land navigation they are generally not sufficient.
A protractor is used to measure angles on a map. There are special made protractors for use in land navigation, but you can also use a standard protractor that children use for school supplies. To get a map protractor, check out U.S. Cav.
Pencil or alcohol pen:
When marking on a map, a good pencil is useful. If you have a well waterproof map, you can also use an alcohol pencil. The benefits of this are it's easy to see, can be wiped off with alcohol, and is waterproof.