More Than Just Finding North: Understanding the Compass

by Chris on July 6, 2009 · 20 comments

in Manly Skills, Outdoors, Survival

Minolta DSC

Men go back to the mountains, as they go back to sailing ships at sea, because in the mountains and on the sea they must face up, as did men of another age, to the challenge of nature. Modern man lives in a highly synthetic kind of existence. He specializes in this and that. Rarely does he test all his powers or find himself whole. But in the hills and on the water the character of a man comes out.

Abram T. Collier

While none can argue that the rapid advances in technology over the last century have drastically improved the lives of modern men, there are negative consequences that also accompany these advancements.  For the average man, it is often the case that as our technology has increased, our knowledge has subsequently decreased.  The skills that were known to every man just two or three generations back have withered, and technology has become a crutch.  The advent of the internet and the all powerful Google has put worlds of knowledge at our fingertips, but as information becomes more and more readily available, man has no motivation to retain it within himself.

The real problem is not whether machines think but whether men do.

B.F. Skinner

While the positive aspects this unprecedented access to knowledge surely outweigh the negatives, there is something to be said for retaining some of the skills of yesteryear.  It is with that in mind that we turn our attention to relearning the use of an old tool, one which guided men through the darkest jungles and the most unforgiving seas for generations…the compass.  In the following sections we will review the construction and handling of the compass and will examine the technique for basic compass-based navigation.

Basic Styles

While there are several variations of the compass available, two models stand out as the standard equipment for hikers and other outdoorsmen: the baseplate compass and the lensatic compass.

Baseplate Compass

Baseplate Compass

Liquid Filled Lensatic

Lensatic Compass

Both styles rose in prominence during World War II, with the lensatic model becoming U.S. Army standard issue during that time and remaining so today.  The instructions for use that follow will be based on the lensatic model, since it is the more durable of the two.  However, the basic concepts involved in navigation by compass apply to both models.

 

Breaking It Down

Parts of the Lensatic Compass from 1956 Army Field Manual

At first glance, the lensatic compass can seem a bit daunting.  Covered in various markings and with multiple moving parts, it looks as though it demands a high level of skill to operate.  Quite to the contrary, with a little bit of knowledge of the basic functions, anyone can work a lensatic like a pro.

There are three main parts to the lensatic compass; the cover, the base, and the reading lens.  The cover is essentially the lid, and contains the sighting wire.  The base is the bottom half of the compass, and contains the floating compass dial (with markers for South, East, and West and an arrow pointing North), the bezel that surrounds it, and the thumb loop.  The dial itself is actually floating in liquid, usually kerosene or a type of oil.  Protecting the dial is a glass cover with a fixed index line etched into it.  There is also a smaller line on the lens that rotates with the bezel.  The reading lens is mounted in a moveable arm attached to the base of the compass, and folds to lay flat on the dial for protection when the compass is closed.

How to Hold the Compass

Using proper technique when holding the compass is critical, since an improper hold will result in a bad reading, potentially leaving you lost in the wild.  There are two predominant techniques for properly handling a lensatic compass when taking a reading; the centerhold technique and the compass-to-cheek technique.

The Centerhold Technique

Centerhold Technique

To properly execute the centerhold technique, you need to open the compass a full 180 degrees, so that if you were to lay it on a table both the base and cover would lie flat on the table surface.  Now fold the thumb loop to its fully opened position and grasp the compass as shown in the diagram above.   As you stand with your elbows tight at your sides, the compass should be held out in front of your midsection.  To take a reading, point your entire body at a target object in the distance while holding this stance.  Once you are centered in on the object, look down and take note of the degree marked underneath the fixed index line on the dial.

The Compass to Cheek Technique

Compass to Cheek Technique

The name alone leaves little to the imagination, and combined with the above picture, this technique is virtually self-explanatory.  With the cover opened up to 90 degrees and the reading lens opened to 45 degrees, fold the thumb hook to its fully opened position.  Place your thumb inside the thumb hook and grasp the compass with a grip as shown above.

To Take a Bearing

Grasp the compass with your preferred grip.  Locate the target object (distant mountain, radio tower, etc) you will be using for a bearing.  If you are using the centerhold technique, point the compass at the target.  If you are using the compass to cheek technique, locate the object by looking through the sighting wire, centering the sighting wire on your target.  While holding this position, take note of the degree mark.

Navigating with Your Compass

Compass shooting azimuth

Once you have noted the degree mark, rotate the bezel until the moveable line etched into the glass lies directly in line with the north directional arrow.  You have now oriented yourself.  Regardless of visibility, you will always know that when the north arrow is lined up with this line, your target object is in the direction of the sighting wire.  Be sure to retake your bearings whenever you can, so as to leave as little room for error as possible.

Other Things to Keep in Mind

  • Always remember that since a compass takes its readings from magnetic energy, it can be affected by metal objects nearby.  For example, if you’re standing with a kit full of metal tent poles on your back trying to take a reading, you may get a false north and end up walking laps around Yellowstone all day.
  • Be aware of high tension power lines, making sure to be at least 50 yards away from them when taking a bearing.
  • Always check to make sure that your compass dial is able to move freely and that your compass is free of any damage that may interfere with readings.

Of course, this is just an introduction into what you can do with a combination of a compass and proper training.  A detailed guide to more advanced compass techniques can be found in any Army Field Manual, available online or at your local bookstore.  Keep in mind that while a GPS unit is very handy, circuit boards do short circuit and batteries do run down, and when they do, you’ll be glad to have your trusty compass in hand to guide you home.

: United States Department of the Army Field Manual No. 3-25.26

{ 20 comments… read them below or add one }

1 Shaun July 6, 2009 at 8:57 pm

For those that are interested, there’s a discussion about the softening of men and the decline of survival skills going on in the Philosophy group in the Community section. Feel free to have your say!

http://community.artofmanliness.com/group/philosphers/forum/topics/question-of-the-day-33

2 Ike July 7, 2009 at 12:11 am

I am constantly surprised at how few people know the art of the compass. Since I am in Eagle Scout, one of the critical skills we are required to have is knowledge of all types of compasses. I always carry one with me, just in case.

3 Dan July 7, 2009 at 10:25 am

Very nice,
I have spent many a day and night lost in the freaking woods on one of our lovely military bases, cursing the lensatic compass. I always found the most difficult part of land navigation to be the pace count over different forms of terrain. So hooah! Get out there, get lost, and learn something about yourself. And as for night land nav, leave that to the brave and the crazy.

4 Alexandre de V. July 7, 2009 at 6:11 pm

I always have a compass in an accessible pocket of my bag. Even though I am always in the city, I take it out to instantly know my way when I walk out a subway station, or to know what direction is north when driving. I learned a basic compass trick in wilderness suvival class : when I walk into woods, I take a second record the bearing on the compass before leaving the trail. If I get lost, I just have to follow the opposite bearing. When I reach the trail, I only have two possible ways home. Chances are, walking 5 minutes in one way or another will allow me to find a familiar landmark.

5 P July 7, 2009 at 7:02 pm

How did the author completely forget to explain that the user must compensate for declination from true north? Since magnetic north is not the same as true north you must add or subtract a certain number of degrees, depending on where you are, to compensate. Many of today’s compasses have an adjustment that can be made to compensate. Google the declination in the area where you are using it.

6 Cobby July 7, 2009 at 8:48 pm

Another resource is “Be Expert With Map and Compass”:

http://www.amazon.com/Be-Expert-Map-Compass-Orienteering/dp/0020292651/ref=sr_1_1?ie=UTF8&s=books&qid=1247013864&sr=1-1

While I agree generally with P regarding declination, it’s helpful to know whether it makes a difference where you are. Along the Appalachians it’s minimal. Out west you’d better know about it.

7 oracle989 July 7, 2009 at 9:15 pm

It’s a shame more men aren’t familiar with the use of a compass. Just think how lost some of these people would be if we had an outage of the GPS constellation, which is old and very well may shut down.

8 Travis July 8, 2009 at 8:03 am

What brand is the compass at the top of the article?

9 BP July 9, 2009 at 2:07 pm

Can’t say enough about having some man skills. Went orienteering with some people this summer and many of the “men” did not know the sun rises in the east and sets in the west. When handed a map you would have thought it was in Arabic.

10 Michael T July 9, 2009 at 8:46 pm

Take a flying lesson and one of the very first things you will get hammered into your brain is that the wet compass (liquid filled) is the most accurate thing in the aircraft. I don’t know for sure what the exact explaination about this is but I do understand the general point.

May I respectfully suggest that before learning to use a lensatic, get the most basic compass as shown here and learn to use it and how it will behave. It makes a huge difference to just learn the basics.

Oddly enough, one of the things that helped me get reaquanted with my love for “old school tech” (I collect slide rules) was the cheap compass I put in my car, it was less than US$5 and held on with a suction cup. Just to be able to pull out a map on the side of the road and be able to answer the question “Which way am I heading?” can be very educational and helpful.

11 P July 10, 2009 at 11:08 am

Reading Michael T’s post reminded me of my father and grand father. They always had a water compass mounted to the windshield of their cars. They are so much better than the digital ones that come in cars. You can get an exact bearing. I had one in my first car but since buying a new one, I have not had one yet. I think I will buy one today. My dad is so fanatical about these things that he took his altimeter from his first plane and built a mount that would replace the ash tray in his car. It was the coolest thing ever. We could see the barometric pressure, the altitude and the bearing. It was an old school GPS! LOL

12 Chris July 11, 2009 at 12:12 pm

I just returned from an 11 day trek through northern NM, Let me tell you, if we didnt have a compass, we would have been lost on dat 1. We were using the basic base plate compass though.

13 Dave July 12, 2009 at 5:15 pm

The baseplate compass shown at top, also called a “protractor” compass, is a Silva. Brunton makes one that’s almost identical, and I’m sure other manufacturers of quality compasses, do, too. The beautiful compass in the top picture is called a box compass. You won’t even find them for sale anymore. I’ve used all three types, and a few more, extensively.

I recommend the baseplate/protractor compass over the lensatic for a beginner. I use a Silva Ranger Model 15, far more compass than you’ll need unless you’re doing professional work. It’s about $50, and it’s deadly accurate. For most purposes, you can get a good, liquid-damped baseplate/protractor compass for under $15. Just make sure that it has some means of adjusting for declination. I recommend you go to a good outdoor store that specializes in backpacking, etc. I do not recommend the cheap lensatic compasses that you can find for, oh, $10 or so. They’re not worth it.

I can’t emphasize enough, though, the importance of magnetic declination. I’m out west, and the declination in my area is about 15° East — enough to throw you waaay off, and get you into some deep doo doo. But once you understand it, it’s easy to handle. In some places in the Pacific Northwest it can be 20° or more.

A compass does one thing that no GPS receiver can do. With a compass you can determine where something is without going there, by triangulation. GPS’s are cool. But I never go into the woods, or backpacking, or anything like it, without my compass.

14 Kyle July 14, 2009 at 8:41 am

The one thing I like about this site… it makes me think there is still hope. Just about all the skills and knowledge they share in here are things I think my generation is lacking… and therefor the one under me is lacking even more in! I think they said it right when they refered to my grandfathers generation from WWII as the last grgeat generation. They knew how to do this… somehow along the way, it has become a rare art for a man to be a man and not need GPS or to call a fix it company to do his work.. and dont even get me on how folks raise kids these days!

15 Cobby July 15, 2009 at 2:07 pm

Here’s a site that provides declination from a zip code:

http://www.ngdc.noaa.gov/geomagmodels/Declination.jsp

16 zombie July 17, 2009 at 2:21 pm

When I reach the trail, I only have two possible ways home

17 Christopher Hutto July 17, 2009 at 5:38 pm

Hey love this article. I came across another forgotten navigation tool that can do much more than a compass and is just as invaluable if you have proper knowledge of its functions it is called an Astrolabe. The Astrolabe is very cool and makes being without electricity or clocks a breeze, I believe that the U.S. Navy still uses it in their basic training.

18 Martin August 15, 2009 at 9:51 pm

THanks Dave.

Every article always has one guy add a comment that send me into action. Your comment is the one for the compass article.

I will get the baseplate/protractor compass. Not sure where but will look around. This article and your comment was helpful I know nothing about this but this may come in handy one day.

19 Dave August 23, 2009 at 9:47 am

Thank you, Martin, that is the highest compliment.

Re: looking for a compass – a decent outdoor sports store, particularly one oriented toward backpacking, should have a good selection, and a clerk who knows what s/he is talking about. If you can find a “Recreational Equipment Incorporated” (REI) (“The Co-op”) store near you, that is a great place to go. But Bass Pro, Scheel’s, Cabella’s, etc. and a host of local backpacking shops will also have what you’re looking for.

Two other things — I didn’t mean to badmouth lensatic compasses, only cheap ones. A lensatic compass is fine, but IMO takes more skill to use well. And the good ones can run you a C-note. You get more bang for your buck with a protractor/baseplate design.

Second, I said that the compass should have a means of “adjusting” for declination. I should have said “compensating” rather than “adjusting.” I recently had a friend use a compass that had a scale on the bottom of the capsule, and you simply placed the North end of the compass over the appropriate mark rather than straight at the “N.” There’s no adjusting – just compensating. That does work. On the other hand, the compasses that have a means of actually adjusting and setting declination sure are convenient. That’s how it is with my Silva Ranger 15 CL. But, as I said, unless you’re using a compass professionally, the Silva Ranger is overkill. Not that I’ll ever part with mine…

20 Ben K May 11, 2010 at 11:37 pm

Good info and can be a lifesaver. It is indeed strange to think that some people don’t know how to use a compass. It’s kinda like when someone sees me carrying my knife (which I always do) and wonders what I could ever use that for. Or wonders why I would ever keep a set of tools, a sleeping bag and survival kit in the trunk of my car.

I grew up flying, boating, snowmachining and hunting. All using dead reckoning with a compass. We use GPS now but you’d better believe we have our “analog” instruments ready for when the batteries die. I guess growing up in rural AK will do that for you.

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