Learn Map & Compass with Andrew Skurka, Part 1: Adjust for declination & orient a map, by SierraDesigns Gear on YouTube. 4 min 39 s.
- Video length
- 4 min 39 s
- Time to do it
- 15 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Look up the current declination for where you are hiking. Use a recent map margin note or an online declination calculator, and note whether it is east or west.
Find the declination adjustment on your compass. On most baseplate models it is a small screw or key on the housing that turns the orienting arrow inside the capsule.
Turn the adjustment until the orienting arrow is offset from the capsule's north line by your declination amount. Set east declination by rotating the arrow east of the line, west by rotating it west.
Check the setting against your map. Many topo maps print the declination diagram in the margin so you can confirm the direction and degrees.
Place the map flat and set the compass on it. Line up the compass edge with the map's north-south grid lines or the printed north arrow.
Hold the compass steady and turn your whole body and the map together until the magnetic needle sits inside the orienting arrow. Keep the map flat as you turn.
Now the map is oriented. Its features line up with the real terrain, so a ridge on the paper points at the same ridge in front of you.
Use the oriented map to identify peaks, valleys and trail junctions. Match shapes and positions, then confirm with your compass bearing before you walk.
Tips and common mistakes
Declination changes slowly over time, so use a value from the last few years rather than an old map margin.
If your compass has no adjustable declination, add or subtract the declination by hand each time you take a bearing.
Keep metal objects, phones and magnets away from the compass, since they pull the needle off north.
Recheck the needle against the orienting arrow after you move, because the map can shift in your hands.
Questions
What is declination in simple terms?
It is the angle between True North and Magnetic North at your location. Your compass needle points to Magnetic North, so you correct for that gap with the declination setting.
How do I know if my declination is east or west?
Check the declination diagram on your map or a declination calculator for your area. East declination means Magnetic North sits east of True North, and west means the opposite.
Do I need to reset declination when I travel?
Yes. Declination differs by region, so look up the value for each new area and adjust the compass before you rely on it.
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.
