How magnetic declination on a compass works

Posted on February 18 2016, by Scott Gilmore

I was a boy scout. It taught me two things. First, always check the water levels before launching off on a remote river trip (long story). Second, you need to understand magnetic declination if you are going to do any wilderness travel. 

Your compass needle rarely points true north. Due to fluctuations in the earth's magnetic field, it will point to the east or west, depending on where you are. If you're in Maine, your compass will point about 17 degrees west of true north. In Oregon, it'll point 15 degrees east. Doesn't sound like much, but 15 degrees off your bearing can put you a long way from camp. So, it's important to know the declination and make your adjustments. 

There's a great tool to find your declination. The US government's National Center for Environmental Information has a useful site for calculating the current declination for anywhere on the planet. 

And every good compass (like our solid and reliable Lensatic) will allow you to easily adjust the declination. 

Here's a great video by the guys at Black Owl Outdoors that explains it even better than we could. Give it a couple of minutes (it could save your life), and don't forget to visit their online shop.


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