Map and Compass: Lauren finds a somewhat flat section of trail, clears the leaf litter away, and spreads her map on the ground. “The first thing you have to do is orient your map before you can even begin to figure out where you are,” she says. She does this by dialing north into the compass and then lining up the edge of the compass base with the corner of the map. She rotates map and compass together until the magnetic needle floats within the orienteering arrow etched in the middle of the compass dial locked on north. That’s when, according to Lauren, “Fred is in the shed.”
By the time Lauren stands up to “shoot” her first bearing in order to triangulate her position, the four minutes it took for Tim to fix his location have just expired. Clearly, triangulating your position via map and compass takes time and patience—a slide rule would work more slowly than an electronic calculator.
Fortunately, Lauren finds two visible geographic features she can use in her triangulation. In the ensuing 20 minutes, she takes bearings off the two peaks she’s identified and transfers those coordinates onto the map. She does this by pointing the compass at one peak and turning the dial until Fred is in the shed again, and then notes the coordinates. It’s 266 degrees for Middle Moat Mountain and 287 degrees for North Moat Mountain.
But those are not the final coordinates. “When going from real life to the map, you have to add declination,” Lauren advises, referring to the rule in the Eastern U.S. “When going from the map to real life, you have to subtract declination.” (The opposite is the case in the Western U.S.) Declination is the difference between true north and magnetic north, and it’s noted in the map legend. Lauren does the adjustment manually, by scratching out some quick math with her pencil on the side of the map. Most compasses—even basic models—can be set so that the orienteering arrow aligns with magnetic north, while the pointer remains calibrated to true north. This can save some time when shooting a bearing, since the reading you take will already account for declination. Since a GPS device uses satellite signals to fix a position, declination doesn’t come in to play.
The challenge with triangulation, Lauren says, is that you have to be sure you are shooting the right peak or peaks, so you need to possess some idea of where you are. You also have to keep tabs on how and when you add or subtract declination and be ready to plot and trace multiple bearings on your map until your lines intersect at a point you feel confident about. That can take some time—about 24 minutes for Lauren.
Lauren says she could have used just her map, and, like Tim, noted where the trail turned, where the stream was, and where the contour lines were bunched more closely together, which indicate steeper sections of trail. Having a map to check terrain features and noting how those features change while on the trail can often be enough information to determine a general location. But, when in doubt, Lauren says, “Triangulation is how you find where you are with map and compass.”
Challenge #2: Peak ID
At 1.9 miles, we reach the summit and a 360-degree panorama, obstructed only by a sparse collection of stunted pine trees rooted amongst rock slabs, shrubbery, and grass. I ask Tim and Lauren to identify as many peaks as they can in the immediate vicinity, using their navigation tools. Lauren goes first.
Map and Compass: Kneeling on a flat boulder, Lauren orients her map to true north before securing it with rocks and a water bottle placed at the corners. To identify peaks using compass bearings, she says, you need to know where you are standing. (She knows she’s on Peaked Mountain since we followed a trail to the top.)
From the summit, she points her compass at a dominant peak to the west and shoots the bearings. Then, she places one corner of the compass on the map’s Peaked Mountain and rotates it until the needle is in its house. The pencil line she draws along the compass edge intersects with Middle Mountain. Her first peak is identified.
She repeats this process several times, formally identifying all mountains easily visible and notated on her map. It takes only 10 minutes.
“It’s really a combination of how far you can actually see without things being in the way and knowing how to read contour lines,” Lauren says, “because that’s really what’s going to help you identify things.” In fact, once the map is orientated to north, she adds, “you could figure out a lot of things without bringing a compass out.”
GPS: “The big difference here is my compass is saying north that way,” Tim says, “and my GPS is saying north that way.” He’s pointing southward now, exactly opposite of his compass bearing, so he walks in circles for a few seconds to allow the GPS to reset. (It couldn’t determine his direction of travel when he was standing still.)
It’s a 30-second exercise that demonstrates exactly why a map and compass are so vital. Tim’s GPS indicated good signal strength—it was connected to several satellites. Without a compass to check the accuracy of his device, Tim might have assumed the GPS reading was valid—a dangerous assumption deep in the backcountry.
With a reading of north confirmed by his compass, Tim uses the digital compass on the GPS unit’s screen to align his map with north and then pockets the GPS. He proceeds to identify the same peaks that Lauren did using only the map and the view as references. The total time is six minutes.
Map and compass. Photo by Pete Ingraham.
