A compass is one of the “10 Essentials” you should have in your pack if you are heading into the great outdoors to recreate. Carrying a compass is never a bad idea, but like most tools, you need to know how to use it. Don’t be one of those people who lose their bearings in the woods and can’t find their way out. Arm yourself with some basic map and compass know-how so you can keep yourself on the right path.
Types of compasses
There are three basic types of compasses that vary in price and functionality. Hikers and other outdoor adventurers should consider paying more for a baseplate compass, which is designed to work with a topographic map.
Basic compass: A basic compass only has a fixed 360-degree dial and a magnetic needle. This type of compass can distinguish between north, south, east, and west, but it is not accurate enough for precise navigation. A basic compass should only be used in an emergency or as a backup. It is portable and affordable, making it easy to clip to your pack.
Sighting compasses use a mirror to help you find a bearing to a distant object. These compasses are highly accurate for finding bearings in the field, but they don’t work well with a map. They are used mostly by foresters and the military. They are more expensive than a basic compass and require some practice.
A do-it-all compass, the orienteering compass takes the best of the signaling compass and adds the ability to use it with a topo map. These compasses have a clear baseplate that allows you to place it on top of a map. They also can be used in the field without a map. The orienteering compass is more expensive than a basic compass and about equal in price to a signaling compass.
Parts of a compass
There are four parts of an orienteering compass — the base plate housing, the magnetic needle, the direction-of-travel arrow, and an adjustable dial with degrees. Depending on your model, you may have other features, such as a ruler or a magnifying glass to view items on a map.
Base plate: The base plate is the main body of the compass. It is typically clear so that you can use it with a map.
Magnetic needle: The magnetic needle always points north and is often colored red. It should float smoothly inside the compass and not stick.
Adjustable dial: Also called the Azimuth ring, this circle has 360-degree markings as well as the cardinal directions of north, south, east, and west.
Direction-of-travel arrow: As its name implies, the direction-of-travel arrow is used to indicate the direction you want to travel. You can use it in the field or on a map. Not all compasses have a direction of travel arrow.
What is a bearing?
In simple terms, a bearing is the direction in which you need to walk. It is written in degrees based on a circle. North is 0 degrees or 360 degrees, east is 90 degrees, south is 180 degrees, and west is 240 degrees. You should know how to find a bearing as well as walk according to a bearing.
Finding the bearing to an object in the field using a compass
Being able to find a bearing is a critical skill every outdoor person should know. If you are lost, you can use it to find your way out of the woods. First, you need to find an object to which you want to walk. It could be the road you see below you or a large field you see in the distance.
- Hold your compass steady in your hand, so the baseplate is level and the direction-of-travel arrow is pointing forward, away from you. Keep the compass about halfway between your face and waist. Hold it in a comfortable arm position with your elbow bent and the compass held close to your stomach.
- Turn yourself and the compass so the direction-of-travel arrow points toward the tree, road, or another landmark.
- Look down at the compass and turn the compass dial so the compass needle lines up with the engraved orienting arrow (or as the saying goes, “put red in the shed”).
- Read the bearing off the top of the compass and walk according to the bearing using the instructions below.
Walking according to a bearing
Once you have a bearing, you can easily walk long distances on that bearing. In this example, we will use a bearing of 180 degrees, but you can use any bearing you want when you do this yourself.
- Set your compass to the bearing of 180 degrees by turning the azimuth dial so the direction-of-travel arrow is lined up with the 180-degree marker.
- Hold the compass in front of you and turn your body until the compass needle lines up with the engraved arrow in the compass dial (put red in the shed).
- Pick an object (a tree, a rock, or another visible object) that is directly in line with your line of travel arrow.
- Walk to the object. Don’t look down at the compass, as you will stumble and fall. When you reach your chosen object, we need to find another object in the distance that is at the same bearing.
- Again hold your compass in front of you and turn yourself so the compass needle lines up with the engraved arrow (put red in the shed) on the compass dial.
- Pick an object directly in a straight line from your line-of-travel arrow. Walk to the object.
- Repeat this sighting and walking process until you have reached your destination.
Directions and declination
Declination is simply the difference between true north on a map and magnetic north, which is what your compass detects. It is critical to know about declination when you are using a map and a compass for navigation. Maps are drawn based on true north, while compasses use magnetic north. In the northeast United States, the difference between true north on the map and magnetic north on the compass is a whopping 15 degrees. If you don’t adjust your compass for declination when you are navigating with a map, you could get widely off course.
Most inexpensive compass units do not allow you to adjust the compass for declination. You have made this adjustment by adding or subtracting the declination value from your bearing. This calculation can be confusing, especially when you are in a survival situation.
To avoid adding or subtracting the declination, you should use a compass with a built-in declination adjustment. Once you adjust your compass declination for your location, you don’t have to worry about declination again. Remember that declination changes as you travel. Don’t forget to change the declination when you visit a new location.
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