Tuesday, January 10, 2012

Always carry a compass, even on day hike

Like a paper map, a compass is indispensable even if you use GPS. Should your GPS no longer function, the compass then can be used to tell you which direction you’re heading.

A protractor compass is best for hiking. Beneath the compass needle is a transparent base with lines to help your orient yourself. The compass often serves as a magnifying glass to help you make out map details. Most protractor compasses also come with a lanyard for easy carrying.

The compass and a map can be used in a number of ways, but the most basic skill (and you’ll find the most useful on a day hike) is orienting the map properly. This will help you better understand which features are around you and give you a better idea of where the trail is heading. To do this, simply place your map on a flat surface. Next, place the compass on the map. Shift the map around until its line pointing “north” matches the north on your needle. The map is now oriented to the terrain.

A compass does have a one major issue: declination. Compass needles point at magnetic north, but maps use grid north. The difference in degrees between the two (usually listed on topo maps) is known as declination. You will have to rotate your compass dial to find grid north. If you don’t, the discrepancy will cause you to walk several miles in the wrong direction. This usually is not significant on a day hike trail with kids, but if the declination is large, you could become confused when taking a compass reading and comparing it to a map’s grid north.

Another problem with compasses is field interference. Metal on your equipment can cause the needle to point the wrong direction. Always use a compass away from metal.

Read more about day hiking with children in my guidebook Hikes with Tykes.