I found these recommendations a while back when I was researching techniques for using a magnetic compass. A small error when using a compass can result in a significant error in measurement on the ground.
To obtain accurate readings when using a compass:
- Ensure the compass has been adjusted for declination.
- Hold the compass level and steady so the needle swings freely.
- Hold the compass about waist high in front of the body, except when using a compass with a sighting mirror or a sighting type compass.
- Raise and lower eyes when taking a bearing, do not move your head. Always use the same eye when taking bearings.
- Directly face object that is being measured.
- Magnetic fields will give incorrect compass readings. Avoid taking readings near magnetic fields such as steel, iron (ferrous metals), vehicles, rebar, and clipboards. Even belt buckles, glasses, and rings can interfere with the compass reading.
- Take bearing twice.
- Adjust for magnetic declination as appropriate.
- Follow the direction of travel arrow, not the compass needle, when walking a bearing. Always follow the line indicated by the compass rather than relying on judgment as to the direction.