Rugged handheld GPS units and, more recently, iPhones and other mobile devices seem, at first blush, to be great substitutes for a lightweight backpacking compass. That may be the case for a short hike on a well-known trail, but serious adventures require a compass (and a map) in addition to a handheld GPS. Here's why.
GPS Units Need Movement for Accurate Directions
Directional readings will vary wildly when standing still or moving very slowly, which is not very helpful if you are standing on top of a mountain trying to figure out which direction you are facing.
Some handheld GPS units and newer iPhone models have built-in electronic compasses that work independently of GPS satellite communications through a technique called magnetic induction. These electronic compasses detect the Earth's magnetic field, producing the same result you would get with an analog compass. Accuracy of sophisticated electronic compasses for marine navigation can be very high (to match the 4-digit price tags), but don't expect more than 2 to 5 degrees of accuracy with your handheld GPS or mobile device compass.
GPS Display a Limited Amount of Fine-Scale Information Unless You Zoom Out
Trying to figure out your location on a small GPS or iPhone screen can be challenging in a backcountry environment (especially if you lose satellite coverage!). Plotting courses on a paper map not only works without satellites, but allows you to view topography information over a broad area without zooming in and out. Another reason to bring along a compass is that it is difficult to accurately plot bearings on a map with a GPS or phone.
GPS Is Power Hungry
The possibility of a handheld compass breaking or malfunctioning is smaller than with a GPS or other mobile device. Some GPS units are very rugged, but there are still more things that could go wrong (like forgetting the spare batteries). The best strategy is to refer to your map and compass frequently, checking your battery-hungry GPS as a backup and to store waypoints.
GPS Units Need Movement for Accurate Directions
Directional readings will vary wildly when standing still or moving very slowly, which is not very helpful if you are standing on top of a mountain trying to figure out which direction you are facing.
Some handheld GPS units and newer iPhone models have built-in electronic compasses that work independently of GPS satellite communications through a technique called magnetic induction. These electronic compasses detect the Earth's magnetic field, producing the same result you would get with an analog compass. Accuracy of sophisticated electronic compasses for marine navigation can be very high (to match the 4-digit price tags), but don't expect more than 2 to 5 degrees of accuracy with your handheld GPS or mobile device compass.
GPS Display a Limited Amount of Fine-Scale Information Unless You Zoom Out
Trying to figure out your location on a small GPS or iPhone screen can be challenging in a backcountry environment (especially if you lose satellite coverage!). Plotting courses on a paper map not only works without satellites, but allows you to view topography information over a broad area without zooming in and out. Another reason to bring along a compass is that it is difficult to accurately plot bearings on a map with a GPS or phone.
GPS Is Power Hungry
The possibility of a handheld compass breaking or malfunctioning is smaller than with a GPS or other mobile device. Some GPS units are very rugged, but there are still more things that could go wrong (like forgetting the spare batteries). The best strategy is to refer to your map and compass frequently, checking your battery-hungry GPS as a backup and to store waypoints.
About the Author:
Interested in learning more about why you should have both a compass and GPS? Go see Compass-HowTo.com to learn all you need to know about this and many other compass topics. You'll find compass reviews and recommendations, and resources for learning how to use a compass.
