Land Navigation Part 3: Compass and Pace

Sergeant First Class Roner was probably of average height, or a little above, but thanks his bearing he seemed tall. He had broad shoulders and the lean build of an all-round athlete, and a mop of curly black hair that was cut by a barber who knew what he was about. He completed the image with gold-framed and mirrored Ray-Bans, a Rolex Submariner, and a set of camouflage fatigues that were tailored just enough to underline the fact that he took pride in his martial appearance, and not too much so we could all see that he was not a garrison soldier who would dress impractically. On the instructional podium, which is where we knew him from, his native Panamanian accent was offset by a natural actor’s — or maybe a trained one’s, for all we knew — projection and diction. He was altogether the sort of thing we called Hollywood, which in our circles was not a term of endearment.

And we might have been just a wee bit jealous, because SFC Roner already had his, and he was a gatekeeper who stood athwart our path to having ours. Special Forces qualification, that is. In a minute he was going to release us on the Day Land Nav course, aka the Star Course, and in the next three days or so about half of us would be gone.

Rrrolex time isss,” he announced, and gave us the time hack. One of the other instructors had tried to hand him a bullhorn; he didn’t take it. He didn’t need it; we were so on edge that he could have whispered, but his voice carried across the broken camp. “You have eight hours from release… in five, four, three, two, one go!” 

And at that most of the guys went. Some of us took a moment to confirm an initial azimuth and then we trotted off, counting each step. Over the next two days we’d walk, run or jog almost 50 kilometers by day and 18 in the dead of night, with ruck, rifle and gear, hitting multiple points, each one usually miles from the last. It was hit the points, or hit the truck. You didn’t want to hit the truck.

How did we do it? With two essential tools: compass and pace, and an ancient form of navigation called Dead Reckoning. Dead Reckoning depends on the principle that if you begin from a known point, and then make a movement of a given azimuth for a given distance, there is only one point you can be at when you stop.

In a flat, unobstructed world, all you would need is a map, to plot your start and end points;  a compass, on which you could set your azimuth; a pace count, which translates your steps into real distance; and willingness to trust those tools, to go to anywhere you can walk to on land.

In the real world, there are more problems but there are also more tools you can use. The difference between the graduates and the recycles (or NTRs) at SFQC was often those extras, because by this point, you had map, compass, and pace count down. 

The Map and Azimuth

GI Declination Diagram

This is a declination diagram (this one’s from this post, where the use of one is explained).

Plotting your course on the map requires you to know where you are. (There are various ways to determine this, if you’ve become, in Daniel Boone’s terms, “a mite bewildered.” But let’s assume arguendo that you know that, for now). And it requires you to know where you’re going.

Now, draw a line between Point X and  Point Y — if you can go straight. (You might need to make your course several shorter legs because of obstacles). If you must make a turn, make every effort to make it on a recognizable terrain feature. “I’ll be on the summit of this hill, and when I turn to my new azimuth there will be low ground on three sides and a saddle on my right.” Note the distance. “It’s 1700 meters.” Now do the next leg, and so on to your destination. Time spent plotting is never time wasted; you’re impressing the expected terrain in your mind. (Maybe not the first time you do it, but soon enough, with practice).

Now go back over your legs and look for additional checkpoints. “At 700 meters, on the first leg, I cross power lines. From there it’s 1000 meters to my turning point on the hill. On the second leg there’s a lake on my right; it should be closest to me at about 2100 meters down that leg.”

Military protractor

Military protractor

The azimuth? It’s simply the angle at which your course diverges from magnetic north. But your map is marked with convenient grid lines that are not aligned with magnetic north, so you have to adjust your grid azimuths to magnetic azimuths. Failing to do that, or forgetting the step because you’re too tired, is a traditional ticket out of Special Forces training and down the road to the 82nd Airborne Division. NTTAWWT.

The Army provides two cheats that help you determine your azimuth. One is a clear plastic square with 360 degrees marked on it, called  a “protractor,” and the other is the “declination diagram” on the map which tells you how much grid north is offset from magnetic north right here and right now. Many models in the Silva compass line include a clear base with similar markings. The instructions for using the declination diagram are marked right on the map, but most folks will never do it successfully in the field if they haven’t done it at a desk at least once before. But if you do it right, you now have a map azimuth for each leg.

MARSOC (er, Raider) Special Operations Officer 0370 candidates in training. USMC Photo.

MARSOC (er, Raider) Special Operations Officer 0370 candidates in training. USMC Photo.

Time spent plotting is never wasted, and shortcuts in plotting will not help as much as you think.

The Compass and Azimuth

Compasses usually have some kind of ring that you can set so that the north-seeking arrow is aligned with magnetic north while some indicator on the compass points towards your destination — or at least your next checkpoint. This ring in the service is called the “bezel ring” which is redundant, but there it is. (The compass maker often uses just “bezel.”)

Silva type compass

The Silva compass is practical and simple, although it’s not as effective for two purposes as a genuine military lensatic: for such things as calling artillery fire or otherwise taking a bearing, one, and for use at night, because the military compass includes tritium ampules in the needle and orienting indicator. (You can get some after-dark use out of the Silva by sticking luminous material to the base to backlight it). The Silva is great at picking up your azimuth from the map for you (remember to correct for declination with military maps and as needed).

silva-compass-1-2-3

It can be difficult walking in a straight line in some environmental conditions. For example, in forest you cannot see very far. So, line up your azimuth, pick a prominent tree in line with your azimuth, walk to the tree, and shoot the azimuth again, pick a tree — repeat as needed. Once you have your tree or other target picked out, you can just walk there and don’t need to play with the compass. (When you’re new at this, you’ll probably do a lot of crosschecks as your confidence builds. That’s OK!)

In this manner you can walk straight and avoid being turned around, even when you have to walk for miles and miles.

Pace Count

OK, so we’ve solved half of the polar-coordinate problem that is navigating by Dead Reckoning, to wit, azimuth, or, for the vocabularily challenged, “the left-right thing.” So we know where to go; how do we know then next piece of vital information, when to stop? We do it by counting our steps.

To establish your pace count in a given terrain (and while bearing a given weight, because load-bearing changes your gait), you need to count your steps over a known distance on similar terrain. Walk the same distance course several times in both directions, then average your total steps, then reduce to a rate of steps per 100m.

Then, when you’re walking, count your steps by the hundreds of meters, mentally cross-checking the expected terrain. When you make it to 100m, by pace count, note that and start counting again. At first you will constantly cross-check terrain against your pace count (“Should I be crossing a road at 450 meters?”), but in time you will come to use it confidently.

Put it all together, and with map, magnetic compass, and pace count you can go anywhere (well, you’ll have problems in the far arctic or antarctic. But in the temperate, tropical and subtropical latitudes most of us dwell in, you’ll be pretty mobile cross-country.

There are advantages to this. Most of humanity, and in First World countries almost all of humanity, is road-bound. With a map, a compass, and two good legs, you are not.

44 thoughts on “Land Navigation Part 3: Compass and Pace

  1. Boat Guy

    We all call it “Dead” Reckoning but I was taught some time ago that it was “Ded” Reckoning the “Ded” short for “Deduced” which makes sense.
    Good explanation. Reminds me that I need to confirm/ascertain what my “Old Guy” pace is.

    1. ToastieTheCoastie

      It has always been “dead” reckoning. Why it is “dead” I don’t know exactly. Possibly because when you’re DRing you are flying blind so to speak.

      1. Kirk

        It’s a controversial subject, but the spelling has been “dead reckoning” going back to the 1600s. The “deduced reckoning” thing came up during the early days of air navigation, and dates to the 1920s.

        http://www.straightdope.com/columns/read/2053/is-dead-reckoning-short-for-deduced-reckoning

        I think the actual meaning for this term is lost in time, in terms of old-school sea navigation. I suspect that the term “dead” refers to the idea that your position was determined by calculation, and did not include the effects of things like actual tide and current, which could only be estimated. So, when you said you’d made your position by dead reckoning, the inputs were “dead” in the sense that they weren’t “really real”, you were guessing at them. A “live reckoning” would be one taken from reality, where you could take sun and star shots, as well as look at landmarks in order to determine where the hell you were.

        Like as not, it’s one of those intuitive things that came over into common usage from a specialized technical field, and because nobody talked about it and just “knew” what it meant from context, nobody really bothered to preserve the actual etymology. Kinda like we don’t know if the Romans marched in step, or not… You assume they had to, but there’s a total lack of any preserved evidence that they either did, or did not. It was just one of those things everyone assumed everyone knew–Until, they didn’t.

        1. JAFO

          I learned about dead reckoning in boats, in a maritime family. The way I learned it is that it was your position relative to an object assumed to be dead in the water at your starting point, based on time and course(s) made good. In the days before satellite based nav systems, your DR was the only way to keep track of your position between celestial fixes out of sight of land. It’s still a good idea to run some sort of DR as a sanity check against the electronic stuff no matter where you are.

          When you’re using pace counting in hilly terrain, do you compensate for shortening of your pace going uphill, and lengthening downhill, or just assume that it will pretty much be a wash? How about in swamps, or snow?

  2. Boat Guy

    We all call it “Dead” Reckoning but I was taught some time ago that it was “Ded” Reckoning the “Ded” short for “Deduced” which makes sense. Good explanation. Reminds me that I need to confirm/ascertain what my “Old Guy” pace is.

  3. Boat Guy

    I’ll also note that I have never outgrown my fondness for “Compass, Lensatic” -despite having acquired some Silva’s over the years.

  4. S

    Add in….counting paces with a mechanical pace-counter or a more reliable knotted para-cord pulled through a hole in the pocket. Also, knowing how to fix a bearing by sun or star, in whatever hemisphere you’re in, with or without a watch. How frustrating is it to fix the base course by a glance at the watch, and a glare at the DS, who grins back, knowing all the while that whoever is actually “navigating” is dooming the entire party to an extra half-day meandering through the cowpats, and daring you to speak a word? The real test of dead reckoning that was laid before us, was the spectre of having a shelter half draped over the head and, issued a compass, given a destination…and this wasn’t SF, it was normal infantry fare, Aussie style. Things have changed now, and not for the better. Once upon a time, infantry did things, but now they must sit in the FOB while Special People get to go do the Special things. Maybe Special isn’t so Special as it once was? I suspect Special means more “deniable”, these days, than it means, “more capable”. For all the hatred we have for Stilwell, in some ways, he had a point. Anyway, for some of us there looks to be a supplementary test, far too old as we are, but the passing grade is the same. No flags for our shoulders, no resupply or exfil, but perhaps having a better reason “why”. That should make all the difference, and the “how” will come along on its own.

  5. Cap'n Mike

    This post brought back eough memories that I had to dig out my old map case. Most of my outdoor time is spent on the water nowadays, but I really miss walking around the woods.

    I would like to get a military map of my current AO, are they readily available?

    1. Boat Guy

      USGS are as close as I’ve been able to find on the open market. Pretty good.

    2. Kirk

      Actual DOD-style maps aren’t printed for areas the military doesn’t see a need to operate in. The digits are out there, on CD-ROM, but the actual maps themselves…? Nope. You’d need to find an Army Topographical company, and talk sweet to the guys in the printing shop. I’m not even sure you can order the damn things from the GPO, to be honest–A lot of the maps we needed for work up on fire crews in the National Forests had to come from the Topo company, and even they couldn’t ramp up to produce them quickly enough. What is in print are mostly around military installations and National Guard training areas. The rest of the country? On a hard drive, somewhere.

      That said, you can get maps printed up using the next best thing to MGRS, which is UTM. The grid lines will be the same, depending on datum they work from, but the coordinate systems won’t be. You may have to draw in your own gridlines, but there are a bunch of civilian outfits that custom-print maps who will included UTM if requested.

      You can find the limited number of available 1:50 000 NGA maps at the USGS Store site under “NGA Foreign and US Maps”, and then looking for your area. You might get lucky, but the available maps in print are pretty slim–Like I said, limited to where they foresee military operations being conducted, or where they’ve been requested for.

    3. DAN III

      Cap’n Mike,

      “….a military map of my current AO, are they readily available ?”

      They sure are ! Any scale from 1:10 thru 1:50. Custom sized per your request at their website. Laminated, not laminated, etc. Very reasonably priced and extremely fast service, i.e., a few days from date of Internet order.

      Go to: http://www.mytopo.com

      You’ll be amazed.

  6. medic09

    Nicely done series!

    I learned rudimentary map and compass skills as a boy. When I was a soldier, we didn’t have enough lensatic compasses to go ’round. And they always warned us how expensive they were if lost. But I always carried my trusty old baseplate compass, and found that for most nav problems it was fine. There are some nicer (but inexpensive compared to lensatic) models with mirror and site notch that do a very suitable job. They also fold closed to a thin package that fits easily in a pocket. GPS is a great tool, but I still won’t go out without a compass (and map if available). Doesn’t need batteries, doesn’t weigh much or take up much space. Gets me from point A to point B, even under thick cover.

  7. John M.

    “So, line up your azimuth, pick a prominent tree in line with your azimuth, walk to the tree, and shoot the azimuth again, pick a tree — repeat as needed.”

    One tip here: when shooting azimuths from tree to tree, alternate which side of your bearing tree you walk around each time you shoot one. If you are consistently going around the right sides of your bearing trees, you’re putting yourself off-course.

    -John M.

  8. John Distai

    So is the 82nd Airborne full of ADD guys? Would a guy with ADD be able to remember his pace count?

    So I take it you can’t use a pedometer?

  9. B

    And when I was 14 we were taught this in Boy Scouts. They called it “Orienteering”.

    B

  10. LSWCHP

    I have two GPS devices, but I never go out into the weeds without a topographical map, compass and protractor.

    Interestingly, the grid to magnetic conversion mnemonic I was taught for navigating in Australia was Grand Ma Sucks..ie Grid to Magnetic Subtract, which is the opposite to what is shown in the graphic. I guess it’s a southern hemisphere thing.

    Also worth noting is that the magnetic variation drifts over time. The fixed variation on the chart will have a note that says something like “Variation increases 2 mils per annum” which can make a big difference if your map data is 30 years old.

    1. Bush in Oz

      LWSCHP, I was taught exactly the same mnemonic at OCTU Puckapunyal back in the mid 80’s, Grand Ma Sucks, Grid to Magnetic = subtract, and the other mnemonic was to visualise a MGA Sportscar ( old 1960’s English sportscar ) : Magnetic to Grid = add.

      This must be a north v south hemisphere thing, maybe someone who has operated in both north and south hemispheres can clarify?

      1. LSWCHP

        I first heard that mnemonic at Holsworthy in 1979. I wonder if it has has survived into the modern PC age?

      2. S

        It depends where you are relative to magnetic north, which is currently somewhere northwest of Greenland and accelerating toward Siberia. Ever since Prince Trudeau ascended to the Canuckistanian throne it has left Canadian Antarctic Territory, and depending on the results of the 2016 El Presidential election, may achieve light-speed and depart the galaxy altogether along with whatever sense and freedom still cowers un-noticed in dark corners of the FUSA.

        The Norteamericanos have to deal with the lineup of magnetic and true north, so they can’t use the catchall GMS mnemonic….the old girl is as confused as their bathroom politics. West of L Superior Granny sucks, but in points east she blows. In California she is actually Grandpa, whereas in Washington the compass spins around aimlessly, just like everything else.

        Something that has disappointed me is the difference in magnetic dip; my trusty southern Silva drags its north along the bottom of the case here in the uncivilised north, so I had to buy a new one for my edc kit. Wish I had the cash for a Brunton Geo set for universal, then again I’m not likely to go anywhere far or soon so it’s moot.

        1. Bush in Oz

          S,
          Thank you for the clarification, so it is not a North or Southern Hemisphere thing, but east or west thing, and as Australia is west of L Superior ( a long way west ) we do the Grandma Sucks mnemonic.
          On this basis would American troops have been taught both rules (sucking and blowing) depending upon whether they were operating on the west coast vs east coast?

          1. S

            They’d better be looking at the legend on the map every time, to be safe. It isn’t just the continental US, it’s anywhere on the line where the one point occludes the other. The magnetic pole hasn’t been wandering with the same speed, either, so the variation rate on old maps will be off. This page has some good info, and stats on where the poles have been:

            https://www.ngdc.noaa.gov/geomag/GeomagneticPoles.shtml

  11. Pingback: WeaponsMan: Land Nav Part III – Compass And Pace | Western Rifle Shooters Association

  12. John Campbell

    Dead reckoning comes from early maritime use – originally

    The LOG (with cord attached) is thrown overboard so it is DEAD in the water. As the cord pays out the KNOTS in the cord are counted for a given time. This gives speed and add bearing to give velocity

    The meanings have changed/been refined

  13. raven

    Be aware a compass can flip poles. I have an old silva that did this reversal-apparently storage next to a ferrous metal can cause it. Or maybe a magnet? It can be disconcerting to have white point north, till it becomes apparent there is simply no way it can be correct. In certain types of terrain, in certain types of weather, it might not be possible to know, however.
    Remember that WW2 found in the Libyan Desert, way beyond any reasonable search? IIRC, the speculation was they flew past the ADF transmitter and did not notice the needle flipped 180 and they were now flying directly away from it. Sort of the same concept.

  14. Lost Dog

    Regarding determining pace count – way back when I was taught we established 2 different pace counts. One for relatively flat terrain and one for steep slopes – we were in areas that varied abruptly from valleys to mountains. We had to make relatively detailed sketches, so knowing distances between particular surface features was important.

    So is it uncommon to use 2 different pace values for flat/steep terrain in land nav?

  15. John Parker

    I don’t get it. I can’t find those contour lines or grid squares anywhere when i am out in the woods. Bunch of BS.

  16. GQ

    Good Post and back to some profoundly geeky roots. Get ye-sef a Declinating compass (Silva Ranger) for all land nav work. Most Lensatic’s are ancient and the jewel that the compass rose sits on gets worn. The “new” ones the Army has are junk. Get a Brunton if you crave accuracy. Teach the morter men how to use it while your at it. Have a cheap, spare compass for when you lose, break, throw the other one off a cliff. The really cheesy ones that slide on a watch band work well and make orienting your map to Mag North as you move fast and accurate. Get a Sunnto Vector for Altimeter Navigation. Plus small children, when you have to associate with them, seem to like it. Slide the cheap compass on the band and now navigation in limited terrain is transformed from a counting and math problem to; real movement. If you want to learn good land nav skills, go the the AMWS in Jericho, VT.

  17. S

    Orienteering as a sport will test your nav as well as your fitness. I tried discussing it with some stratospherically higher ranks once, suggesting that a little less rugby and a little more solo compass and fiendish sketch map/puzzle work might be more useful for light infantry in the modern world.

    Thankfully, field punishment No. 1 is no longer officially inflicted in the modern Army, but when a fully hatched Colonel asks you in an ominously nonchalant voice “Do you like marching in the hot sun?”, you know you’ve royally screwed yourself…..both answers are equally wrong. Don’t forget to pack lots of water and socks, and next time get to know your enemy better before opening the big trap….

    1. Bush in Oz

      S,

      Thanks for clarifying that issue and providing the links to the NOAA websites. Some great information at those websites.

      1. S

        You’re welcome, Bush. Enjoy a gum-scented misty dawn for me, especially if the maggies are singing.

  18. dangero

    One thing I can’t stress enough is how perishable a skill this is. When I went to PLDC at Ft. Lewis as a young E-5 I was a land nav stud. I was the 3rd guy back and had found all my points because I was doing it regularly. Fast forward a short 2 years later and I had received a direct commission and went to Ft. Benning as a butter bar for BOLC. Land nav practice day came and I was chomping at the bit to show these officers how it’s done. Well 3 hours later I came out of the woods having found ZERO points, I broke my map case, and some how lost my eye pro. It was humbling but I realized how out of practice I was, pace counts don’t come naturally over rough terrain and I was sloppy with my azimuths.
    Thanks for these write ups, you’ve inspired me to get back out there and brush up.

  19. PSYOP Soldier

    I must say, that i have thoroughly enjoyed this topic, as it brought back memories, good ones, of LandNav phase, having passed it…It was a bitch however…One of the most satisfying things i did while enlisted…They told us that if would successfully navigate in and around Mackall/Uwharrie, then we could do it anywhere due to the subtlety of the terrain, relative to the topos…Did a lot of terrain association too, very tough, as a hill on the map, did not always look like a hill on the ground, or depression, etc….

    Talk about a huge confidence booster, and something i carry with me to this day.

    I have complete faith in my GI Issue, lensatic compass, tritium based unit, built like a tank, always dependable…I also keep the Cammenga Tritium Wrist Compass w/Black Wrist Band – J582T on some fly line around my neck as back up…great for basic direction of travel, etc…

    I keep it in my suv, with various other kit, and when i hit the mountains of WNC, and i am heading out to stalk trout in remote areas, have it tucked, along with local topo in my vest, just in case…

    1. Hognose Post author

      Yeah, the land nav training provided at Bragg to SF and the other SOF guys there including Psyops/CA (who are SOF or not depending on the whim of some two-star or other this week, I think) is much better than what they do in say IOBC or Ranger School — the Ranger School land nav test is a doddle.

      And yeah, the relatively low relief of the terrain in the Hoffman Triangle brings you to an A game.

      1. Chris

        Went thru CA school in ’98. Land nav and Nasty Nick were my two favorite parts of the course.

    1. Hognose Post author

      There are two ways to divide up a circle: into degrees, where everybody does 360, which is close enough for land navigation, and into mils, a more precise measurement for using for, for example, artillery fire control, or surveying. Russian and former Soviet practice has 6000 mils in a circle. NATO practice is to use 6400. Mils approximate miliradians, which are actually about 6283 to the circle. (2000*π).

      Russia uses 6000 because they used to use a cruder system in Tsarist days and the Soviet system is a metricated and more precise version. NATO uses 6400 because US uses 6400, US never used mils before World War I and adopted them (along with most of our artillery weapons and practices!) from France.

      If you look at the Russian protractor, you will see it is marked in degrees and in Russian mils.

      1. RostislavDDD

        Yes, “thousandths”.
        The secret is simple. “The division of the circle, 360 degrees -to 6000, slightly reduces the accuracy greatly but simplifies the calculations.” Tsar gunners knew their business.

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