Magnetic Declination Explained | Your Compass Needle Does NOT Point North!, by TheTautLine on YouTube. 5 min 13 s.
- Video length
- 5 min 13 s
- Time to do it
- 10 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Find the declination value printed on your map, usually in the margin diagram. It shows the angle between true north and magnetic north and whether it is east or west.
Note the date on the map. Declination shifts slowly each year, so add or subtract the annual change to get the current value.
Turn the compass over and find the small declination adjustment screw on the baseplate. Use a coin or small screwdriver to turn it.
Rotate the housing until the orienting arrow inside points the correct number of degrees east or west of the index line.
Check the setting against your map value. The orienting arrow should now sit offset from the meridian lines by your declination angle.
If your compass has no adjustment screw, hold the compass and turn the bezel so the orienting arrow is offset by the declination amount.
Mark the offset on the baseplate with a pencil or a strip of tape so you can reset it quickly.
Take a test bearing on a known landmark and compare it to the map. Adjust the setting if the two do not agree.
Tips and common mistakes
Remember the correction: subtract east declination and add west declination when converting from magnetic to true north.
Recheck the declination value every year or two because it drifts by a few minutes of angle annually.
Keep the adjustment screw clean and dry so it does not seize up in cold weather.
Questions
What is magnetic declination?
It is the angle between true north and magnetic north at your location. Your compass needle points to magnetic north, which is usually not the same as the north on your map.
Do I add or subtract declination?
It depends on direction. When going from map bearing to compass bearing, subtract east declination and add west declination. Reverse the rule when going the other way.
Can I use a compass without a declination screw?
Yes. Turn the bezel so the orienting arrow is offset by the declination amount, or do the math by hand each time you take a bearing.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
