   |
          |
Duke of Edinburgh's Award
Bronze - Compass
While most of the time it is sufficient to use just a map to find your way around the countryside, when it is foggy, dark or there are many paths to choose from, a compass can be used to help to determine which direction to walk in
Above - The parts of a compass.
The compass describes direction as the number degrees from magnetic north from your location to your destination.
A compass always points to MAGNETIC north, a field of strong magnetic attraction created by the Earth spinning. As the Earth does not spin exactly on its axis, magnetic north is continually shifting its position. It is currently just north of Hudson Bay in Canada. However, maps are drawn to GRID north which is currently east of MAGNETIC north. The number of degrees that GRID north and MAGNETIC north varies is called the MAGNETIC VARIATION and varies depending where you are in the country. OS maps always give the exact MAGNETIC VARIATION for the area. Check and remember this before using a compass with a map. True north is at the north pole, but this has no relevance in navigation.
Taking a grid bearing and converting it to a magnetic bearing can be used to check that the direction of the path on the map matches the direction of the path on the landscape and can be used to choose the correct path to take when there are many to choose from.
With the magnetic bearing set you can also walk on this bearing if the path is unclear or non-existent, sighting to features along that bearing, then walking to it, and repeating the process.
Above – Taking a Bearing (or trying to)
Taking a magnetic bearing and converting it to a grid bearing can be used to ensure that the path you are travelling on matches the direction of path on the map. If there is more than 10° difference then you are probably on the wrong path. The compass can then be moved about to see which path on the map most closely matches the bearing to identify which path you are actually on. It is also used to do resections.
The compass can also be used to set the map. Place the compass on the map so the N is at the top of the map. Then rotate the BOTH the MAP and COMPASS until the red needle points north, the map is then set. There is no need to consider the magnetic variation.
Click HERE to return to the D of E Home Page