Choosing the Right Compass
There comes a time in life when you realize that trying to give directions using “right” and “left” is confusing and ineffective. It’s especially ineffective if you’re trying to navigate outside of an urban area. Learning to read a compass and to build compass terms into your vocabulary is a critical survival skill.
Direction 101: Cardinal, intercardinal and secondary intercardinal points
The four main points, or cardinal points, on a compass are North, South, East and West. There are four intercardinal points on a compass that indicate the direction halfway between two cardinal points. These are Northeast, Southeast, Southwest and Northwest. Easy right?
It gets tricker. You’ve probably heard your local weather person or NOAA’s “Metal Mike” using ambiguous sounding terms like “North-Northeast” or “South-Southeast” when describing a storm. These are secondary intercardinal points that indicate a direction halfway between a cardinal point and an incardinal point. If you really want to be a smarty-pants you can keep going with secondary intercardinal points all the way to something like “East-EastEastNorthEast-EastNorthEast” but chances are you’re going to get left behind in the wilderness if you do that.
Types of compasses
Compasses aren’t all created equal. The big bulbous things most of us had in our cars before cars came with digital compasses are different than the kind of compass you’d want for hiking. These compasses have a rotating paper card or a plastic ball that rotates around a metal needle. As you turn, the card or ball stays put and you only see the metal needle moving. These compasses are fine for driving but not for survival.
Apple’s iPhone app uses two devices inside the phone to operate the digital compass: One is a magnetometer that measures changes in the Earth’s magnetic field and the other is an accelerometer that tracks movement. The app combines the heading information from the magnetometer with the roll and pitch data from the accelerometer to determine the exact orientation of the iPhone. There are problems with Smartphone compass apps though – keep in mind that you won’t always be able to get reception.
If you’re using a compass for survival you want a good mountaineering compass with these features:
- A moveable orienting arrow
- A transparent base plate with a ruled straight edge and a travel arrow or a sighting mirror
- A bezel marked clockwise from 0 to 360 degrees
- Parallel meridian lines for plotting a course on a map
Reading a compass takes a little education and practice. The American Hiking Society has a great downloadable PDF that explains the anatomy of a compass and how to use it when plotting by sight or by map.