How to Take a Bearing from a Compass
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Posted by Aspiring Ninja | Jun 17, 2020 | Standard, Survival Navigation
Maybe it has been a while since you got your Merit Badge in Orienteering. Perhaps you never got that far in Scouting and are mildly curious about how to use a compass. Or, you feel you desperately need to find out all you can about that magical, magnetic device in the bottom of your bug-out bag.
Whatever the reason for reading this article, at the end of the day, you will be armed with an adequate amount of information about your compass, and will be able to use it with the degree of confidence needed in a survival situation.
First, a short story to establish my compass creds. Back in 1985, my infantry platoon in Ft. Lewis, Washington, was tasked with laying out and operating a compass course to educate and evaluate the latest crop of R.O.T.C. Cadets. From the base of a gently sloping hillside, we paced off four zig-zag courses up the hillside in four different lanes.
At each zig, (or zag), a paper plate with a large number painted on it was nailed to a tree, along with compass directions and distance to the next paper plate. A total of 5 points were set, with the last point at the top of the slope directing the three-man teams straight back down the hillside to the beginning point. Easy enough. After the classroom sessions were over, the Cadets were put through their paces on a daylight run through the course.
Thanks to my platoon’s excellent instructional skills, most of the Cadets found their paper plates, recorded the numbers and made their way back to the starting point.
Then came the night course. Team lanes were switched, and the Cadets began their way up through the course. All lights at the base of the hill were blacked out, so they could not use the base as a reference point. Through night-vision goggles and thermal sights, we watched the teams negotiate the course. Lanes 1, 2 and 4 were progressing nicely, if more slowly than in daylight.
Lane 3, however, started having problems from the start. The team missed the first point by a long shot, and their zigs were twice as long as their zags. It was not long before they crossed into another team’s lane, backtracked across yet another and at one point compassed themselves in a complete circle. It was going to be a long night.
Through the thermal and starlight sights, we were able to determine their mistake. Just before each turn, there was a blinding flash of light. It was evident that in the darkness, the compass man was using a metallic cigarette lighter to see the compass dial in the dark.
The compass needle, being magnetic, automatically pointed to the lighter, throwing off their readings by more than a few degrees. Teams 1,2 and 4 made it back to the starting point with respectable times, reported their paper plate numbers, and took the rest of the night off. Team 3, however, was allowed to crash through the wilderness until 2325 hrs., at which time the lights were turned on, and by megaphone they were called back to the base of the hill. They were then lectured about their mistake, ridiculed a bit, and allowed to re-take the course the next night. You can be sure they passed the second time!
Hopefully, you have already learned something about using your compass. When taking a bearing, keep it away from any other metals!
The compass we use today has changed only by design in the last 2,200 years. The first compass invented by the Chinese was a needle magnetically charged with a loadstone and floated in a bowl of water around 206 B.C. This was not used as a compass as we know it, but more of a novelty used in fortune telling and geomancy, or the reading of natural elements like dirt patterns. In the 11th century, they began using the compass as a navigational tool, and the rest of the known world learned how to use a compass around 1190 A.D.
Eventually, the four cardinal directions (North, South, East & West), were named, and assigned positions at right angles to each other on the compass rose, a design printed on maps and nautical charts to indicate map north. North on the compass is 36, or 0o, and each cardinal direction in a clockwise direction increases by 90o, thus East=90o, South =180o, and West=270o.
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A bearing is an imaginary line drawn from your chest, through the center of the compass, extending over a rotating bezel, through the direction of travel arrow, and off the edge of the base plate out to infinity. To take a bearing with an orienteering compass:
Sounds simple, right? But what if you have an Engineer’s or Lensatic Compass? Same basics apply, but the compass is held up to your eye and you read the bezel through a small peephole. The U.S. Military Lensatic Compass Instruction Booklet has instructions for three different methods of using an Engineer’s Compass.
Another thing I should mention here is that there are three really Norths to concern yourself with when orienteering, not just one.
Practicing local deviation will not get you kicked out of your Prepper group, but it will get you nominated as ‘Compass Man’ if you master the art of deciphering the three Norths.
One important thing to learn when studying how to use a compass is how to find your present location on a map of the area you are in. To do this, you stand in one spot, with your map laid out in front of you in a northerly orientation. Slowly turn around until you see a recognizable landmark, like the top of ‘Old Smokey’. Locate Old Smokey on your map, then take a bearing on it with your compass. If your bearing is more than 180o, subtract 180 and record the number.
If your bearing is less than 180o, then add 180. The resulting number is called a back azimuth. Orient your compass on the map. and draw a line from Old Smokey in the direction of the back azimuth. Do this again with another landmark, and the point where the back azimuths meet will be your approximate location. Finding three landmarks will give you a very accurate fix inside the triangle where the three lines meet.
Doing this correctly will be your first big ‘Ah-Ha!’ moment when learning how to use a compass.
Ideally, you will have a decent topographical map of the area you will be surviving in. Realistically, you may not. No matter, your compass skills can still be useful as you navigate your way to your rendezvous point or base camp.
By taking and recording your daily bearings, distance, and time of travel, you can create your own maps and compare your notes to a real map, when you do eventually come across one.
Waypoints, or easily recognizable terrain features, should feature prominently in your travels. First, determine your intended direction of travel. For instance, say you need to get to a major highway intersection you think is north west of your current location. Orient your compass so that the direction of travel arrow indicates you are looking in a north-westerly direction and record the bearing.
Now look off into the distance and choose a waypoint. A large radio or water tower, bald spot on the mountain, or prominent building. (Do not pick the cloud that looks like a bunny, you’ll get lost in a few minutes.) Begin walking in that direction, looking up every few dozen paces to make sure you are not off course. Check occasionally that you’re still on the original bearing, and not wandering left or right.
At this time, I should mention something about distance. Every survivalist on the move should know his length of pace, or how far you travel in a regular step
Keep track of your steps by transferring pebbles representing mile increments from one pocket to another, or make marks on your walking staff. Or use a mechanical pedometer. Yeah, that is a lot easier. Knowing how far you can travel and how long it will take not only keeps your mind busy, it can help plan your next day’s journey. This is especially helpful if you are meeting another party at a specific location and time.
If your phone didn’t come with an installed compass, there are hundreds of apps out there, for both Android and Apple. And some of them even do a decent job of helping you find your general direction of travel. They use your phone’s accelerometer function to track your direction. Assuming your cell network, or any network, is still functional, you can use your phone’s compass for orienteering purposes.
However, it is still advisable to keep your analog compass skills sharp and use your phone’s app as a backup.
Some free compass apps are pretty basic, others charge up to $6.00 for upgrades like detailed maps, latitude and longitude, altitude, solar and lunar tables and a variety of user interface graphics. Compass apps that use GPS are the most accurate, but may use battery life faster, and will be useless after a massive solar flare or EMP event.
Yes, all cell phone apps work, some to a lesser degree than others. As with anything, you get what you pay for. Some free apps come with battery-draining adware, and some have none. The best compass apps come with features that most of us will never use, like a barometer, altimeter, or a GPS.
If you are used to using an orienteering compass with its see-through plastic base flat on a map, you may find a cell phone compass a bit cumbersome. Another useful feature on some compass apps is a distance traveled log. You can use it to double check your manual stride count to confirm how far you traveled in a day.
If you travel with a couple spare batteries, or have a solar/hand-crank charger, the compass app on your cell phone will continue working as long as there is a signal for it to use. Keep in mind, if you are trying to go ‘off the grid’, a cell phone can give away your position as it ‘pings’ off the nearest tower. Remove the battery when you are not using it, and then use it sparingly, if at all.
If you are learning how to use a compass, an app can be helpful. Use both side by side, practice with one, then the other. Compare the interfaces and functions of each and decide for yourself over your own compass course which is more accurate.
Almost all compasses are ‘accurate’, and their degree of accuracy depends largely on the compass user, his or her degree of understanding the theory of a working compass, and their own accuracy in applying magnetic deviation to get a true and correct reading.
That said, there are a few compasses out there that stand out as being exceptional at what they do. The materials that make up a compass and the features included add to the idea that one compass is better than another. To that degree, we have nominated one of each style (orienteering and Engineer’s) to be the most accurate compass available on Amazon.
With a price tag of $89.00, you would expect a talking compass that reminds you to hydrate. While this compass does not have that feature, it does have many that would be considered over-the-top for an amateur survivalist.
Advertised as a rugged, multi-function compass, the name Suunto has long been associated with quality compasses. Handy inch/mile conversion scales are printed on the clear base, making distance calculations on a map easy to figure.
Hey, if it’s good enough for Uncle Sam, it’s good enough for us. Easier to use than an Orienteering compass, just point & shoot. Aiming through the peephole/wire sight gives a more accurate fix on an object in the distance.
Used by U.S. Military as well as fighting forces and government agencies the world over. Rugged design, temperature range from -50o F to +150o F. Aluminium body with raised number scales along the edges.
As it is one of the four greatest inventions known to man, the compass deserves a place in your bug-out bag. Master its use and you will become a productive and valuable member of your group.
Compasses can be had all day long for less than $10.00, and they make great outdoor gifts for boys and girls alike. Share your knowledge with others and designate an hour of your monthly meetings to teaching short courses on orienteering.
When purchasing a compass, the main things you want to look for are:
The Official US Military Precision Lensatic Compass Instructional Booklet
Wikipedia-Compass
Amazon.com
AndriodAuthority.com
Goneoutdoors.com
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