US Army Training - Individual Land Navigation
Dead reckoning is one of the techniques used by soldiers for navigating cross-country on foot. Personally, I try to refrain from using dead reckoning, as it tends to be inaccurate on foot, due to shifting terrain. A soldier, or any person trekking/hiking, will unknowingly flow with terrain due to fatigue, weight of equipment, and other factors like illumination. The concept and execution of dead reckoning is simple, however I suggest only using it at night when illumination is minimal, or if you are in an unknown location headed towards a possible checkpoint (an identifiable terrain feature). With dead reckoning, the navigator has a known starting point and azimuth he/she is traveling on, and hopefully a known distance.
Using a lensatic compass and map, plot your starting point and end point. Determine your azimuth and record it in your navigation log
or something similar. Stand at your start point, shoot your azimuth using the most accurate means. Pick an object in your path about 100m along your azimuth and move to it. If you know your pace count, be sure to keep it. If not, the average male with a heavy load will use 62. That is, every time your left or right foot hits the ground, count 1. Every 62 should be 100m. To accurately determine your pace count, count every other step along a 400m route and divide by 4.
Simple: Point, shoot azimuth, walk, rinse and repeat. Continue and be sure to check your azimuth often.
Also, when determining your azimuth, be sure to check the declination diagram on your map. It indicates the difference between grid north (north on your map), and magnetic north (north on your compass). This will change depending on your location in the world. All you have to do is add the declination angle to your grid azimuth and that is your magnetic azimuth.
When I am navigating, I write my azimuth and distance on my hand so when I check my azimuth I can glance at my hand in case I forget. Fatigue
is a bitch.
Dead reckoning is only useful if you cannot associate the terrain around you with your map. Dead reckoning is a painstakingly slow way of navigating and should only be used in conjunction with terrain association, and pace count for less experienced navigators.
One more point: Trust your compass. During long range movements you are going to be fatigued, wet, and in pain. Your mind is going to start playing tricks on you. You will be crossing a particular terrain feature, and your going to think, "Hey, I think I should be going this way." but your compass will say otherwise. Trust your compass! It isn't going to lie to you unless you are doing something stupid or have a defective compass.
Note: This use of the term Dead Reckoning is used in the United States Army. The definition may differ depending on usage.