| FOREST Navigational Tools |
Map & Compass Skills
The proper use of a map and compass is essential in many natural resource professions. They are important not just for knowing where you are and where you are going, but for representing field measurements on maps, and for translating map measurements into the field.
Long before the development of Global Positioning Systems (GPS) and other high-tech navigational aids, the compass gave humans an easy and inexpensive way to orient themselves. Before you can use your compass and map to navigate, however, you need to make sure you are familiar with all of the features on your compass.
The following compass exercises are simulations of five essential map and compass skills. These exercises build on each other, so we suggest starting with the first exercise and progressing through them in order.
|
| Magnetic Declination |
Coming Soon! |
| In order to use your compass accurately, you will need to find an important feature in the legend of topographic map-- the magnetic declination for your area. Magnetic declination is the difference between true north (the axis around which the earth rotates) and magnetic north (the direction the needle of a compass will point). |
| Orient a Map |
Go » |
| Matching the orientation of the map to the features on the ground will lead to successful navigation by giving you a better understanding of where you are in relation to where you want to go. It also can be especially helpful when you are trying to identify prominent features from a viewpoint. Your map can be oriented either by comparing the map directly with the terrain or by using a compass to orient to north. |
| Get a bearing from an unoriented map |
Go » |
| A bearing is a measurement of direction between two points. Bearings are generally given in one of two formats, an azimuth bearing or a quadrant bearing.
An azimuth bearing uses all 360° of a compass to indicate direction. The compass is numbered clockwise with north as 0°, east 90°, south 180°, and west 270°. So a bearing of 40° would be northeast and a bearing of 205° would be southwest, and so on.
In this exercise you will be using an azimuth bearing to figure out how to get from point A to point B on your map
|
|
| Project a bearing |
Go » |
| If you have identified somewhere on the map where you would like to head and have determined what the bearing is to get there, there are a few tricks you can use to ensure you stay on the right course to get there.
Most compasses have some sort of sighting system built into them to allow greater accuracy in determining where you want to go. If your compass has a sight, you will orient it the same way as described above, but you can look through the sight at the same time and find an object to walk toward.
By finding an object (such as a tree or large rock) that lies along your path you will have more freedom to go around obstacles (such as large gullies, streams, hills, etc.) without losing track of the direction your are travelling. Once you reach the object you were headed for, sight in on another object along your path, repeating this process until you arrive at your point of interest.
|
| Triangulate a position given two fixed points |
Go » |
| Now you know how to get from point A to point B on a map using your compass... but what if you are not sure where exactly point A is (i.e. you are lost)? These days the easiest way to determine where you are on a map is to pull out your pocket GPS (global positioning system receiver) and have it give you your map coordinates. If, however, you do not have a GPS unit with you or you are not getting good reception that day, you can determine your position quite accurately on a topographic map by using your compass to triangulate between two or more points.
Triangulation is used to locate your position when two or more prominent landmarks are visible. Even if you are not sure where you are, you can find your approximate position as long as you can identify at least 2 prominent landmarks (mountain, end of a lake, bridge, etc.) both on the land and on your map.
|
|
|
