Finding a Compass

In this era of high-tech, satellite-assisted navigation, a compass remains one of the 10 Essentials of wilderness travel. Yes, you may hike for days on a trail and never look at it. So just how essential is it? Entirely. If something unexpected occurs say, you take a wrong turn and no longer know which direction you are traveling a compass, in tandem with a map, suddenly becomes one of the most important tools in your pack. The ability to navigate with map and compass is a necessary wilderness skill, especially if you travel off-trail. Unfamiliar terrain becomes less intimidating when you understand the basic functions of a compass and how to apply them to map-reading. These are skills you need to acquire if you regularly travel in the backcountry.

Types of Compasses

• Accessory compasses: The type found on keyrings or watches, or small round compasses with no base plate. They accurately point toward magnetic north, but are designed more for fun and quick reference than serious
  navigation.
• Basic compasses: Inexpensive, yet quite sufficient for wilderness travel; well-suited for beginners. They have all the essential components but lack some bonus features, such as a declination adjustment or a mirror.
• Specialized compasses: Full-featured models with many extras (a mirror, magnifier, et al.). Well worth the added cost if you are a regular wilderness explorer, particularly one who regularly travels off-trail.

Basic Compass Features
Backpackers customarily use what is known as an "orienteering" compass. ("Orienteering" refers to the act of determining your exact position; "navigation" is the process of determining your destination and guiding yourself toward that objective.) The standard features of an orienteering compass include:

• Magnetized needle, usually the red end of a pivoting compass needle, which points to "magnetic north” (When working with a map, you must adjust your compass for "magnetic declination" the difference (measured in degrees) between true north and magnetic north from the point where you stand.
• The housing (or dial) that contains the needle, the needle's bearing (or pivot) and damping fluid. The fluid protects the needle from jarring and minimizes needle movement during readings.
• Rotating azimuth ring (or bezel). A ring marked with degrees from 0 to 360 that encircles the outer edge of the compass capsule. The "azimuth" is your direction of travel (expressed in degrees) between 2 points. Azimuth and "bearing" have come to mean the same thing.
• Base plate, a rectangular, plastic, preferably transparent base where the capsule sits. Better compasses have rulers (in inches and centimeters) etched into the "straight edges" of the plate. These are helpful when measuring distances on a map.
• Fixed orienting arrow and parallel meridian lines (or, north-south lines), located on the bottom of the compass housing. The O-arrow's directional end is usually red and, coupled with the meridian lines (which you align with the north-south lines on a topographic map), helps orient your line of travel on a map.
• Index line or direction-of-travel line, located at one end of the base plate.

Specialized Compass Features

• Declination Adjustment- a more sophisticated orienting arrow, one that can be aligned to reflect the "magnetic declination" in your area of travel. In many cases a tiny adjustment tool, usually connected to the lanyard, is used to turn a small screw on (or near) the compass housing. When adjusted, the orienting arrow is no longer parallel with the north-south lines; instead, it will be customized for your area of travel. Then, when the north-south lines are aligned on a map, the adjusted arrow will accurately point toward magnetic north, indicating the angle of declination. New adjustments can be made for each trip.
• Magnifying lens- a small lens mounted into the base plate; handy for reading tiny map symbols.
• Sighting mirror- a fold-out surface that can improve accuracy when gauging readings on distant landmarks. It also doubles as a signaling/personal mirror.
• Luminescent indicators- these are good to have on your magnetized needle, on both sides of your orienteering arrow, even on the azimuth ring's 4 cardinal points.
• Clinometer- allows you to measure the angle of a slope; helpful for assessing avalanche hazard and the heights of objects.
• Lanyard- a piece of string that allows you to attach a compass to a belt or pack.

Which One Is Right for You?

• Basic compasses: These models are great for beginning adventurers. People who almost always stick to trails (experienced dayhikers, recreational backpackers) can easily get by with an inexpensive model.
• Specialized compasses: Anyone who makes frequent compass checks knows the value of an adjustable declination arrow. For those who have owned a compass with this feature, there is no going back; a declination adjustment is a must. If your travels regularly take you off-trail, seriously consider spending the extra money for a model that includes this feature.
  A sighting mirror is a nice bonus too.

Can a GPS Receiver Replace a Compass?
A compass and a satellite-based Global Positioning System receiver are complementary tools. A compass does one thing a GPS unit cannot: point toward magnetic north. GPS units equipped with an electronic compass are gradually coming to market. Still, GPS receivers are battery-powered devices that potentially could run out of power. A compass, relying solely on the earth's magnetic forces, has no such limitations. Thus, even if you own a GPS unit, you will always want to carry a compass as well. GPS receivers are excellent devices. They are designed to measure direction of movement by calculating the difference between your current position and last position. They can also tell you your position without relying on visible landmarks for bearings.
On days of snow or heavy fog, that's a big plus. Another GPS advantage: When following a bearing via compass, obstructions sometime cause you to stray from your ideal line of travel. This requires you to keep careful track of any deviations you take from your bearing, to the point of counting the paces you take while side stepping the obstacle. Once past the obstacle you might need to adjust your compass bearing, but key landmarks may no longer be in view. With a GPS unit, however, you can easily obtain a new bearing and reset your compass with a revised line of travel. Bottom line: When you want to know which direction you are facing, you must have a compass.

Compass Tips and Terminology
Metal can distort a compass reading, so be sure to take bearings away from your car, camera or other metallic objects. Metallic interference can easily alter a compass reading by 20 to 60 degrees. So, if you are plotting bearings at a picnic table, check to see if your compass is being exposed to metal bolts or brackets that may affect its accuracy.

Electrical fields (a running car engine, for example) can also throw off the accuracy of a compass.
Be careful where you store a compass. For example, do not store a compass on top of a stereo speaker, which is equipped with a powerful magnet, or a place exposed to strong electric current. Over time, such exposure could demagnetize the needle.

Practice Makes Perfect
Ultimately, there is no substitute for practice when your goal is to improve your navigational skills. Here are some additional steps you can take:

• Study an instructional book on navigation and practice its principles on day hikes, short-haul trips, even during city strolls.
• Take a trip with a navigation-savvy friend and learn all you can.
• Attend a navigation seminar or wilderness route-finding course or enroll in a class
  (often available at local colleges or through local branches of national organizations).
• See if any orienteering clubs exist in your area. Orienteering, popular in Scandinavian countries, adds a sporting element to map-and-compass navigation.
  Part endurance race, part treasure hunt, part mental puzzle, |orienteering events are hosted regularly by regional clubs throughout the United States and Canada. Contact the U.S. Orienteering Federation for information.

A compass remains an essential tool for safe wilderness travel. Strengthening your grasp of map and compass skills through practice and field work will make you a more self-assured backcountry traveler.