Selecting a Compass

A good orienteering compass is a critical piece of equipment. It should have these features:

• Clear base plate that allows you to see the map underneath
• Straight sides for aligning two points or for drawing lines
• Liquid-filled needle housing that keeps the magnetic needle relatively steady when taking readings
• Two arrows:
  • A direction-of-travel arrow, painted on the base plate, is used to point the compass at your destination.
  • An orienting arrow, located in the needle housing, is used to orient your compass to your map.

Understanding Declination

• Topographic maps are drawn to true north (North Pole). However, a compass points to magnetic north, which is in the Hudson Bay area. The difference between true north and magnetic north is called “declination.”
• When true north and magnetic north are aligned, zero degrees declination, the compass needle points to true north. If you’re east or west of zero degrees declination, the compass is not in line with true north.
• A diagram on topographic maps shows whether magnetic north is to the east or west of true north and by how many degrees.
• You can correct for declination when you use a compass and a map to take a bearing, as described later.

Using a Compass To Take a Bearing Visually

When visibility is subject to change, such as from hills or fog, take a bearing on your destination while you can see it. Then, when it’s out of sight, use the bearing to find your direction. To take a bearing:

• Hold the compass level, and point its direction-of-travel arrow toward your destination.
• Rotate the azimuth ring until the orienting arrow lines up with the magnetic needle. Be sure the north end of the needle (usually red) points to N, not S.
• Find where the degree markings around the azimuth ring line up with the direction-of-travel arrow. That degree mark is your bearing.

Using a Compass and Map To Take a Bearing

If you know your current location on the map and want to travel to another mapped location:

• Lay out the map on a flat surface and remove any metal objects from the area.
• Place the flat edge of the compass (the side parallel to the direction-of-travel arrow) along the line between the two points. Be sure the direction-of-travel arrow points toward your destination.
• Orient the map to north.
• Without moving the compass, rotate the azimuth ring until the orienting arrow (indicated by N) and the orienting lines point northward on the map, as indicated by the map’s north arrow or vertical lines.
• Turn the map and compass together until the magnetic needle lines up with the orienting arrow.
• Correct for east or west declination.
  • Rotate the azimuth ring left or right using the direction and the number of degrees given on the map.
  • Do not rotate the compass itself. It’s okay if the magnetic needle does not line up with the orienting arrow.
• Find where the degree marking around the azimuth ring lines up with the direction-of-travel arrow. That’s the bearing to your destination.

Using a Compass To Travel Along a Known Bearing

• Hold the compass level, and rotate the azimuth ring until the specified bearing (such as 240°) lines up with the direction-of-travel arrow.
• Turn the compass, not the azimuth ring, until the orienting arrow lines up with the north end (usually red) of the magnetic needle.
• Follow the direction-of-travel arrow toward your destination.
• Periodically recheck your bearing. Also, recheck your location on a map.

Another Direction Finder

You can use an analog watch—the kind with hands—to find south. With the watch on a flat surface, rotate it to point the hour hand at the sun. South is the direction halfway between the hour hand and 12. (If the watch is set to daylight savings time, south is the direction halfway between the hour hand and 1.)