Real Life Scenarios... Let's look at some common backcountry scenarios and see how you can use your map and compass to navigate.
Scenario #1 - Lost in the Fog: Okay, you hike in along the trail and then bushwack off trail to a nearby alpine lake to camp. When you wake up the next morning, you are fogged in. You know where you are on the map, but you can't see to find your way out. What you need to do is take a bearing on your map from your known campsite back to a known point on the trail that you can identify on the map. Then follow your bearing through the fog. Here's your procedure:
Taking a Bearing from the Map (Map Not Oriented):
- Lay the long edge of the compass base plate on the map, making a line from the starting point to the destination (from point X to point Y). Since the base plate is parallel to the direction of travel arrow, the base plate can be used to set the direction to the destination.
- Holding the base plate steady, rotate the compass housing until the compass orienting lines and orienting arrow are pointing to true north. Here you see the orienting lines and arrow are parallel to the line from A to B as well as to the map gridlines. 3. Read the bearing (in degrees) from the degree dial at the point on the compass base plate marked "Read bearing here." In this case the bearing is 346°.
Taking a Bearing from the Map (Map Oriented to Magnetic North):
Orient the map with the compass.
- Lay the long edge of the compass base plate on the map, making a line from the starting point to the destination (from X to Y). Since the base plate is parallel to the direction of travel arrow, the base plate can be used to set the direction to the destination.
- Holding the baseplate steady, rotate the compass housing until the orienting arrow coincides with the North end of the magnetic needle (known as "boxing the arrow").
- Read the bearing (in degrees) from the degree dial at the point on the compass base plate marked "Read bearing here." In this case the bearing is 338°.
Scenario #2 - Heading to the Summit: You have been hiking along the trail and found a good campsite that is marked on the map. You see a summit ridge above treeline that looks like a great place for photographs, but there's a valley thick with Douglas fir between you and the summit. What you need to do is take a bearing from your current position to the summit and use that to travel through the forest. Here's your procedure:
Taking a Bearing from the Land:
- Point the compass direction of travel arrow to the destination on the land.
- Rotate the compass housing until the north orienting arrow of the compass housing lines up with the red magnetic needle. This is referred to as "boxing the needle," since you want the needle to be inside the box defined by the orienting arrow. The north orienting arrow must be pointing in the same direction as the red (north) magnetic needle. Your compass will look like the figure above with the needle boxed.
- Read the bearing (in degrees) from the degree dial at the point on the compass base plate "Read bearing here."
Walking a Bearing Taken from the Land:
- After taking the bearing, as described above, hold the compass level and in front of you, so that the direction of travel arrow points to the destination.
- Rotate your whole body until the magnetic needle lies directly over the orienting arrow. Make sure the north end of the magnetic needle points to N on the compass housing. The direction of travel arrow points to the destination.
- Site a prominent feature to which your direction of travel arrow points. Walk to that feature.
- Continue to sight on other features along the bearing and walk to them, until you reach your destination.
Walking a Bearing Taken from the Map:
To walk a bearing taken from the map, you may need to correct for declination if you did not orient the map to magnetic north before you took your bearing. Once you have corrected for declination, follow the same procedure as indicated above for walking a bearing taken from the land.
Techniques for Walking a Bearing:
Sometimes the terrain isn't always so cooperative to let you just follow your bearing in a straight line so there are a number of techniques to use when traveling on a bearing.
Line of Sight - Walk to an obvious landmark-a tree or boulder that is directly on the bearing. Then take another bearing on the next obvious landmark and walk to that. Keep it up until you reach your destination. By going to intermediate landmarks, you minimize the chances of veering off your bearing.
Scenario #3 - Retracing Your Steps to Camp:
You got to the summit and got some great photos, even one of a baby mountain goat. Now it's time to get back to your campsite. You could just follow your back bearing (see below) back to your location, but there is bound to be some error, when you hit the trail where will you be in relation to your campsite? The best bet is to intentionally aim off. Here's your procedure:
Back Bearings To check your position while walking a bearing, you can take a back bearing. Before you start to walk on your bearing, turn around take a bearing 180° off of the bearing you are going to walk. For example, if you are going to walk a bearing of 45°, shoot a bearing directly opposite your course of 225°. Locate some landmark along this bearing. Once you have moved a short distance along your bearing, turn around and shoot a bearing back to that landmark. If you are on course, that bearing will still read 180° off your bearing of travel (in this case 225°). If it doesn't, it means that you are off course. Sailors and sea kayakers use back bearings all the time to check for lateral drift from wind or currents. Back bearings are also useful if you are heading out to someplace and then returning along the same line of travel. There are two basic formulas for calculating a back bearing.