A reliable and accurate compass is the first requirement for land navigation. A top quality compass, one that is rugged and easy to read is an absolute necessity. An orienteering compass, such as a model from the Silva Ranger series or the Suunto MC series, is recommended. Some of the features you will find in this type of compass are clinometers for measuring the angle of a slope, a coordinate scale for plotting locations on a map, and a sighting wire and mirror for line of sight navigating.
Most compasses have scales for measuring distances and a rotating bezel used for setting your azimuth, or direction of travel. More expensive models also come with a built in declination adjustment. Built in declination adjustment saves you from having to physically make adjustments for declination on paper or in your head while navigating. Azimuth and declination will be discussed in depth under the section “using the map”.
A surplus military lensatic compass is a durable option. But in the long run you will pay almost as much for a Silva or Suunto, without all the features. A lensatic compass costs around 40 dollars, where a top of the line commercial compass, Silva Ranger for example, costs about 50 dollars. A simpler, less expensive compass will do just as well as long as you know how to use it.
A wrist compass has a number of advantages- it is easy to orient yourself with it on the run and, being strapped to your wrist, it is hard to lose. Drawbacks of the wrist compass are its inaccuracy and lack of features. Consider carrying both an orienteering compass and a wrist compass as a backup or for quick navigation.
A basic compass can be purchased for about 10 dollars. All compasses come with an instruction booklet. Read this booklet carefully. The compass you purchase may have special features not covered here.
Properly holding the compass insures accurate navigation. Stand with your feet firmly planted, your body square and steady. Be sure to hold the compass level when reading it. When sighting with the compass use both hands to hold it, wrapping the fingers around either side. Hold the compass level, centered in front of you for sighting. Move your entire body to align the compass sight with your objective. Do not move just you arms.
Remember that the compass is magnetic. To obtain accurate readings be sure you are clear of large metal objects, power lines or iron ore deposits. Even a battery powered watch can affect the readings on a compass.
The United States Geological Survey prints maps of the United States and its territories. You can purchase maps olnline, or find general information on maps, map symbols and map reading from the USGS website at www.USGS.gov, or by calling 1-888-ASK-USGS. Follow the linkto the USGS store- 1:24,000 topographic maps are now eight dollars each, 1:100,000 maps are nine dollars each as of March, 2009. You can also contact the USGS Information Services at (303) 202-4700, Monday through Friday, from 8 am-4 pm Mountain time or write to them at:
P.O. Box 25286
Denver, CO 80225
An order form is included in the Appendix.
Most outfitters carry a selection of topographic maps of their local area and will usually special order maps. Bookstores and office supply stores often carry maps as well, although you will pay more at any of these suppliers than you will at the USGS, something to consider if you are buying 10 or 15 maps for a trip.
Most USGS topographic maps are printed on regular paper. Newer releases of more popular areas, such as National Parks and Monuments, are being printed on waterproof, tear resistant Tyvek.
Unless you are using a tyvek map, it is a good idea to keep your map in a waterproof mapcase. These can be found at any outdoor store. A one gallon ziplock bag will work just as well. Fold the map so the area you are working in is visible. This alleviates having to remove the map each time you want to check it.
A pacecord is a worthwhile tool when accuracy in measurement of distance is important. A pacecord can be any piece of cord that can be used for counting by loosely tying knots in it. To use a pacecord tie a knot after each 100 meter interval that you walk. Untie the knots after the tenth 100 meter stretch- you have just gone 1000 meters or one kilometer.
Some outfitters carry beaded pacecords, with the beads taking the place of knots. They can be slid from one end to the other to mark your 100-meter intervals. To use a pacecord you first must know your pacecount, the number of steps you take to cover a 100-meter stretch. To find your pace count, measure out a 300-meter course on the ground. Now walk the course counting every time your left or right foot, whichever you feel comfortable with, strikes the ground.
Once you have this number, divide it by three. This is how many paces it takes you to walk 100 meters, your pacecount. The reason for making the course 300 meters is simply to use averages. You may want to walk the course a number of times to be even more exact.
Remember that your pacecount will change between flat and sloped terrain, travel uphill as opposed to downhill and when carrying a heavy pack. Take this into consideration when calculating distances.
Fig. 1- Military protractor with thread inserted at center for quick azimuth determination.
A protractor (Figures 1 and 2) is used to determine your azimuth, or direction of travel, on the map. Using the protractor will be covered under the section “using the map”.
Some protractors, such as the military protractor in Figure 2(a) have a grid coordinate scale built in. There are different scales for each different scale of map. Be sure you have the proper coordinate scale for your map if you are planning to use one. Plotting of grid coordinates will be covered under the section “using the map”.
Back to Top