Take Bearings From a Map
Finding the direction between one point and another is called taking a bearing. Say you want to find the bearing from Owl Pond to Cherry Knoll (left). Place the compass on the map with the long side of the baseplate in line with those two points; the direction-of-travel arrow (A) should point in the direction of Cherry Knoll. Now turn the dial so the meridian lines run parallel to the map’s north-south lines with, importantly, the orienting arrow pointing map north (B). The number at the index line (C) reveals your bearing. In this case, 45 degrees.
To follow that bearing (called plotting the bearing), hold the compass level in front of you and turn your body until the magnetic arrow aligns with the orienting arrow. The direction-of-travel arrow now points toward Cherry Knoll. Proceed forward, making sure the magnetic needle stays on the orienting arrow. In map circles, this process is known as “putting Red [the magnetic needle] in the shed [the orienting arrow] and following Fred” [direction-of-travel arrow].
Take Bearings in the Field
To find the direction to a visible landmark, hold the compass level in front of you, and point the direction-of-travel line at the landmark. Rotate the dial until the orienting arrow aligns with the magnetic needle. The index line shows your bearing, which you can then plot onto a map.
Decipher the map key
>> Scale Tells you the ratio between a distance on the map and the actual distance. A 1:24,000 scale means that one map-inch equals 24,000 ground-inches, or about one-third of a mile. Most maps also have a graphical bar showing the scale (e.g., 2.5 inches equals one mile).
>> Contour interval The elevation change between each contour line
>> Symbols The markings used to denote trails, streams, mines, etc.
>> Date of publication and revision Reveals how current the map is
>> Magnetic declination The difference in degrees between true north and magnetic north. Since the latter drifts with time, for old maps, get the latest declination at ngdc.noaa.gov/geomagmodels.
>> UTM zone number UTM refers to the Universal Transverse Mercator coordinate system, a grid that’s similar to latitude/longitude but based on the metric system. The zone number indicates which of the UTM’s 60 zones you’re in—vital info for taking waypoints from a map.
Find North with Polaris
Locate the two stars at the rim of the Big Dipper’s cup (called the pointer stars). Draw an imaginary line between them, and follow it (about five times the relative length) to Polaris, the North Star, which is the tail-end star of the Little Dipper. The North Star typically lies within one degree east or west of true north. This only works in the northern hemisphere.
Find True North
Unfortunately, magnetic north (where the compass points) is not true north (the North Pole). The difference between the two (called magnetic declination) varies with location and is listed in the map key. Since most maps are oriented toward true north, you must correct your compass bearings to get an accurate direction. To do this, adjust the orienting arrow on your compass to whatever the declination is (for instance, about 14 degrees east in central Colorado). If your orienting arrow isn’t adjustable, make the correction by subtracting east declinations and adding west declinations to true bearings (“East is least; west is best”). For example, if your central Colorado map shows a 90-degree bearing (the true bearing) to reach a hilltop, you’d set your compass to 76 degrees (the magnetic bearing).
1. Be Expert With Map and Compass: The Complete Orienteering Handbook, by Bjorn Kjellstrom, is the navigation bible. Read it, do the exercises, and stay found. $19; wiley.com
2. The dependable Silva Ranger 515 Compass features an adjustable declination arrow and a mirror for greater accuracy when sighting. $55; 2.4 oz.; silvacompass.com
3. Outdoor Navigation with GPS, by Stephen Hinch. Once you’ve mastered map and compass, make the leap into GPS navigation with this crystal-clear, reader-friendly instructional book. $17; wildernesspress.com
Photos by Courtesy and Julia Vandenoever (Books), Illustrations by Supercorn.