Using a Map and Copmpass
A good friend of mine hiked her first 14’nr here in Colorado on Thursday, and I am quite proud of her! She wrote me a nice email describing her experience, and I am very impressed that she accomplished what she did. Before she left she asked me for advice on what to take, and I told her the basic survival things for that type of a hike: let people know where she will be and when she will be back, a knife, water, first aid, paracord, a way to start a fire, an emergency blanket, water purification tablets, all the usual stuff. She was well prepared, although did say that she could have used more water. Still, she made the trip successfully, and that is an accomplishment.
On a trip like that, most 14’nrs (mountain peaks that are at least 14,000 feet tall) in Colorado have established trails to the peak, so a map and compass aren’t really necessary, but I almost always take a compass with me no matter where I go in the wild, and usually I take a map, even to areas that I know very well, especially when I am traveling far away from camp. I do have a GPS, and I use that too, but being able to use a map and compass is a critical wilderness skill that everyone who ventures into the wild should know. While it can be an extensive topic, there are some basics that are easy to learn.
Maps – The best maps to use for wilderness travel are topographical maps, which consist of lines that outline the contour of the land by concentric circles following the terrain. The U.S. Geological Survey (USGS) maps are the standard from which most other forms of maps or map software are derived. A quadrangle map in 7.5 minute relief covers about 50 – 70 square miles of land, and shows excellent detail to display the land you will be traveling. Not only do the topo maps show the contours of the land, they are also shaded to show vegetation, open space, and water (creeks, rives, and lakes).
While I could write a chapter on understanding maps, here are some basics:
Contour lines: They connect points on the map that share the same elevation, providing a 3-dimensional perspective of the landscape. Tightly packed contour lines indicate steep terrain; widely spaced lines indicate relatively level terrain. Contour lines never intersect.
Contour interval: Contour lines are separated at specific elevation intervals. Intervals may vary by individual map, appearing every 20, 40, 80, 100 or 200 feet. But the interval used on a single map (say, 80 feet) remains consistent throughout that map. A map’s chosen contour interval is identified in the margin of each map. A contour interval of 40 is what I find most useful.
Index contour lines: Every fifth contour line is the index contour line. Usually the line is slightly bolder and intermittently includes the elevation (the number of feet above sea level) of all points on that line.
Scale: The bottom of each map includes a horizontal graphic scale. It displays how a measurement on the map (1 inch, for example) equates to miles/kilometers of terrain covered by the map.
Colors and shading: Darker colors (or shades of gray) represent dense vegetation. Lighter colors (particularly greens) or shades of gray indicate comparatively sparse vegetation. Lighter colors (such as beige) or no colors suggest open terrain. White spaces with blue edges indicate permanent snowfields or glaciers.
Magnetic declination diagram: Printed in the margin of the map, this diagram shows the difference (declination) between magnetic north (indicated by the MN symbol) and true north (or polar north, indicated by a star symbol).
Grid: Numbers displayed around the edge of a map represent two grid systems that can be used to determine your location.
- Latitude and longitude: Exact L&L numbers are displayed in the corners of maps and at equal intervals between the corners.
- Universal Transverse Mercator (UTM): This system, used primarily by the military, divides the earth’s surface into a number of zones.
Combined, all of the above can enable you to determine your elevation, the ruggedness of the terrain around you and the most desirable route to travel to reach a destination.
Sometimes the quadrangle maps don’t always cover the exact area you want, the area you want to hunt, fish, or hike may be covered by sections of multiple quadrangle maps. So you may have to buy a few quadrangle maps and cut them to fit the specific area you want, and then tape them together. I did this with the map I will be using this September for elk hunting, and it is precisely what I need, and has lasted over 20 years.
Compass – Now that you have a map, you need to know how to use a compass to find your way once you understand the map itself. First of all, a compass will always point to magnetic north, so be sure to account for that by checking the magnetic declination on your map, which is usually displayed in the lower right corner of the map. A compass makes wilderness navigation possible by enabling you to accurately gauge directions from your current position to identifiable landmarks throughout the terrain that surrounds you.
The most basic function a compass provides is pointing north (magnetic north). An orienteering-style compass (click here to see one) allows you to assign a numeric value (a “bearing”) to any direction in the 360° circle around you. This means you can head toward a specific spot rather than simply ambling “south-southwest” or “due east.”
The rotating bezel of a compass is used to convert general compass directions into specific bearings. A bezel’s outer edge includes degree lines which break down the 360° circle around you into 2° or 5° increments. A bezel measures the direction towards a given object in terms of an angle—specifically, the clockwise angle between a straight line pointing due north and a straight line pointing toward the object. This bezel allows you to express any specific direction as a number between 0° and 360°.
Why is it useful to know that your camp lies on a bearing of 40° instead of “to the northeast?” Because precise navigation results in efficiency, safety and speed. Following a bearing off by just 1° can translate into almost 100 feet of error after 1 mile. That means that after a 5-mile hike, you could miss your target by almost 500 feet. In the wilderness, a few dozen feet can mean the difference between spotting a campsite or other landmark and missing it completely.
To find where you are on a map, use the method of triangulation. Triangulation is a technique that involves a map, a compass and two separate landmarks. It can pinpoint your position on your map even if you have no idea where you are. Follow these steps:
- Pick two distant landmarks that you can see and can easily identify on your map. They should be at least 60° apart.
- Take a bearing off of each object by pointing your compass at the object and reading the bearing degree.
- Transfer those bearings to your map by aligning your map to North and aligning your compass to the same bearing.
- Each bearing will form a line. Where the lines cross marks your location.
Wilderness navigation is one of my favorite topics, as you can see from this lengthy post. While there is so much more to write about, these basics should be good enough to get you started on using a map and compass. These skills are not only critical for survival; they can also help you get to places that you see on maps that are miles away with no clear path to get there.