How to Tune a Compass
- 1). Find a location away from magnetic interruption when using and adjusting a compass. Electronic devices exude minor magnetic fields, and while these fields are infinitesimal compared to the earth's magnetic poles, the accuracy of a compass when traveling makes a huge difference even between single degrees of inaccuracy, so any alternate magnetic influences are best left away from the compass.
- 2). Check a current map with declination information for your area. Declination is the degrees of difference between true north and magnetic north. Topographic maps of the sort used in navigation ought to include the declination information for the area of the map, but the magnetic pole constantly shifts unpredictably so only an up-to-date map will help in adjusting a compass.
- 3). Rotate the outer ring on the compass with the degrees printed onto it. Some dials require unscrewing to adjust this dial ring, in which case you will need to find a screwdriver with no magnetism to release the ring for adjustment. Other compasses feature a latch that when released allows the outer ring to move to tune the compass. For an area with a declination of 14 degrees west, for example, the outer ring would have to move clockwise so that the magnetic needle points to 14 degrees to the left of the 360-degree or 0-degree mark on the outer ring.
- 4). Tape a piece of durable tape to the point of declination on a compass which does not feature a moveable outer ring, and regard the taped point as north.
