Map and Compass – AMC Outdoors

June 1, 2009

Hiking through a dense, trail-less section, of Alaska’s Denali National Park several years ago, my backpacking partner and I wanted to pinpoint our location before we settled in one night. We got out a map and two compasses and each of us figured out our whereabouts. Unfortunately these were two very different points about a half-mile apart. We finally came to consensus when we stumbled on a nearby creek we could identify on the map. But not before a few tense where-the-heck-are-we moments.

The moral of the story isn’t that we were unprepared; we did have map and compass with us after all. The problem was that we were mentally unprepared; our orienteering skills had become rusty with disuse and we couldn’t tackle the problem at hand. Do you know how to use your compass?

We asked AMC’s cartographer Larry Garland for his solutions to some common backcountry wayfinding problems.

Problem 1: You need to orient yourself to the landscape. Say you are looking off in a particular direction and simply want to know what that mountain range or river in the distance is. All you do, says Garland, is orient the map to your location by turning it in the direction of a landscape item you can identify so that the features on it lie in relation to where you’re standing. In other words, you want to see the bend in the creek ahead of you in the landscape in the same direction as you have it on the map in front of you. If you can’t easily associate a feature in the landscape with your map, you’ll have to orient the map using your compass, which should then help you discern landscape features or your location.

Problem 2: You need to get a bearing to determine direction of travel from Point A to Point B. If you can see your Point B and need to “capture” that bearing for when you lose sight of it, Garland says simply point your direction-of-travel arrow to the target and rotate the compass housing to “put the red in the shed,” or the arrow in between the red lines. Read the bearing aloud to yourself in case of an accidental brush or nudge of the compass during travel.

If you can’t see Point B directly, you’ll need to determine a bearing from the map—this requires that you can identify both your current location and your objective on the map. Set the edge of your compass on the map along your intended path, making sure you are going from A to B, not the reverse. Holding the compass firmly on the map, turn its housing until the orientation lines under it align with magnetic North. Alternatively, you can turn it until they align with true North, then adjust for magnetic declination.

Problem 3: You’re in a different geographic region and need to reset the declination of your compass. First, a reminder: Declination is the amount magnetic North differs from true North. It varies in different regions and is generally indicated on topographical maps near the scale information. For instance, on the White Mountain Guide maps, magnetic declination is 16.5 degrees west of true North, says Garland. Correct your compass for this amount. For example, rotate the round faceplate dial so that the small arrow above the faceplate dial points to 16.5 degrees west of north. Your compass will now be adjusted for every direction. To find the magnetic declination before you go, visit the National Oceanic and Atmospheric Administration website.

And just a note: You may carry the best GPS unit on the market, but it’s easy to lose—and vital to maintain—your orienteering skills. Also, nothing beats paying attention while you hike. Look around as you go, look behind you, look to the side. Make mental notes of unusual terrain features. See where the sun is in the sky and keep your eyes open. This simple act is a huge piece of knowing where you are and staying found.

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