Declination? Find your true declination and make adjustments simple. Map and Compass made Easy, by David Canterbury on YouTube. 7 min 26 s.
- Video length
- 7 min 26 s
- Time to do it
- 15 minutes
- Difficulty
- Easy
- Steps
- 7
What you need
Steps
Look up the magnetic declination for where you are. Check the declination diagram in the margin of your topographic map or use an online declination calculator for your coordinates.
Note whether declination is east or west and by how many degrees. Write it down so you do not mix up the direction.
Find the declination adjustment on your compass. It is usually a small screw or a rotating scale on the housing.
Turn the adjustment until the compass reads your local declination. Many compasses mark east declination as a positive number and west as negative.
Check the setting against your written value. The needle should now point to true north on the compass housing scale.
Test it on the map. Line the compass edge between two known points and confirm the bearing matches the map grid.
Record the setting and date. Declination drifts slowly over years, so recheck it if you travel far or return much later.
Tips and common mistakes
East declination means magnetic north sits east of true north, so subtract it from map bearings if your compass lacks an adjustment feature.
Do not confuse declination with grid convergence printed on some maps.
Keep magnets and phones away from the compass when you set and test it.
Questions
What is magnetic declination?
It is the angle between magnetic north, where your compass needle points, and true north, the map grid. It varies by location and changes slowly over time.
What if my compass has no adjustment screw?
You can still navigate by adding or subtracting the declination by hand each time you convert a bearing between map and field.
Where do I find my declination value?
It is printed in the margin of most topographic maps. You can also get it from an online declination calculator using your latitude and longitude.
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.
