Refresh Your Navigation Skills - ITS Tactical
 

Refresh Your Navigation Skills

By The ITS Crew

CompassWhether your GPS has run out of power or you’re in a survival or E&E situation, the ability to navigate using a map and compass is one of the most valuable skills you can have and something that everyone should take the time to learn to do.

Maps

Before you can navigate, you need to be able to read a map. While maps come in many different types, the most common map used for navigating is the topographic map.

Topographic maps are characterized by their depiction of contour lines, or lines that show all the points on the map at a particular height above sea level. These lines can be used to gain an idea of the terrain, as they show all the rises and drops in the land.

The closer together the lines are, the steeper the terrain is. For example, in the map below, the terrain is clearly quite steep and mountainous. This is shown by the tightly grouped contour lines.

Another important feature of a map are the Eastings (vertical grid lines) and Northings (horizontal grid lines). These tell you how far north and east a position is on the map and are important in taking bearings.

Nav01

Compass

The most important tool in the navigator’s arsenal is his compass. There are three main types of compasses; orienteering, lensatic and basic.

From L to R: Orienteering, Lensatic and Button Compasses

From L to R: Orienteering, Lensatic and Button Compasses

Orienteering compasses are the best compasses for navigation as they don’t require a separate protractor. In addition to being lightweight, they also feature rulers, magnifying lenses and can be used as a protractor. Orienteering compasses are made by Silva, Brunton and others.

Lensatic compasses are the next best option for navigation. They feature sights which allow for the easy taking of bearings from the viewer to another object. The lack of a base plate however means that a protractor is required for accurate navigation. They are usually very durable due to their metal bodies, but weigh substantially more than orienteering compasses. The most common lensatic compass is the standard GI compass.

Basic compasses have no features other than a needle and dial. These are really only useful in the form of button compasses.

Compasses can use two different units of measurement, Mils and Degrees. It doesn’t matter which your compass uses, except if you’re using a separate protractor, in which case you’ll need to convert your bearings from mils to degrees and vice-versa.

Here’s a link to an online conversion Web site for converting mils and degrees.

Navigation

Step 1 – Where am I?

In order to navigate you need to know where you are on the map.

The best way to work out where you are is by using the features around you. For example, if you were at a bend in a river with a building (black square in photo below) approximately North-West of your position, you can deduce that your are at the red dot.

Nav05

Alternatively you can use the resection sequence method. This is best if your not at a landmark but there are landmarks within sight.

Select three prominent, widely spaced features that can be recognized on the map and on the ground; two features can be used to obtain an approximate position.

On the ground, take magnetic bearings to these features with a compass and convert these to grid bearings (I’ll explain this later). Convert the grid bearings to back bearings (add or subtract 3200 mils/180 degrees).

Using a protractor (not needed with an orienteering compass), plot on the map the back bearings from the identified features. These lines will either intersect to locate your position or form a small triangle of error which will indicate the area in which you are located.

Nav06

Grid and Magnetic Bearings

One very important thing that you’ll need to understand in order to navigate accurately is the difference between Grid North (or True North) and Magnetic North. Maps point to Grid North, compasses point to Magnetic North.

To put it simply, they’re different and you’ll need to allow for this when you navigate. The variation changes over time and differs from place to place. For example, for me in Victoria, Australia the difference is approx. 200 mils or 11.5 degrees. Here’s a link for calculating magnetic variation in the U.S. and abroad.

Some compasses, such as the Silva Ranger have the ability to set magnetic variation/declination so that you won’t have to manually calculate it while navigating.

Step 2 – How do I get to where I need to be?

In order to navigate, you’ll need to take a bearing. If we’re at the red dot on the map below and we wanted to get to the intersection of the road (red line) and the river, the first thing we would do is mark out a line between the two.

Nav07

We then measure the angle between the line and North (orange lines), in this case roughly 60 degrees. If you’re using an orienteering compass, it’s much easier.

Line the base plate up between the two points (you may have to draw a line if the points are far apart) with the arrow on the base pointing in the direction of travel, then twist the compass section around so that the lines and arrow are parallel with the Eastings. (Don’t forget to then change from Grid North to Magnetic North)

Now that you have your bearing, it’s time to follow it. If you’re using an orienteering compass, you’re all set to go, just turn around until the needle lines up with the arrow in the dial and off you go.

If you’re using a different type of compass, rotate the ring of the compass till your bearing is at the top (usually there’s some sort of mark to show where to line it up).

There should be an arrow or some sort of mark in the dial, so turn until the needle is in line and you’re ready to go.

Step 3 – Navigating and Pacing

While you can just stick your head down and follow the compass, this is a very inefficient method of navigating. If your destination is fairly obvious, like the intersection in the example above, you can usually just walk in the direction, checking the compass occasionally.

Another method is the tree method. Line up your compass on the bearing and find a tree that lines up with the bearing. Walk to the tree and repeat the process. if using this method, choose the furthest trees from you in order to minimise the number of stops.

Also, it’s important that when you get to the trees you alternate which side of the tree you walk around, otherwise you can end up veering in one direction.

When navigating with a compass it’s important to count your paces so that you know how far you have travelled, especially on long nav legs. If you’re only navigating a short distance, or there are plenty of distinctive landmarks along your route, then pacing is less important.

While hopefully you will always have access to a GPS, knowing how to navigate with a map and compass is a highly useful skill, and one that you’ll never know when you’re going to need.

Here are some additional downloadable resources provide by Ben Gillies, the author today’s guest post, “refresh your navigation skills.”

Navigational Do’s & Dont’s

Navigation Resection Sequence

Navigation Triangle of Error

Navigation Estimating Distance

Stay tuned for more in-depth articles on the topics covered here today!

Are you getting more than 14¢ of value per day from ITS?

Thanks to the generosity of our supporting members, we’ve eliminated annoying ads and obtrusive content. We want your experience here at ITS to be beneficial and enjoyable.

At ITS, our goal is to provide different methods, ideas and knowledge that could one day save your life. If you’re interested in supporting our mission and joining our growing community of supporters, click below to learn more.

Discussion

  • TJK

    Excellent article.
    To this day, I don’t use a GPS when I go to the Wilderness, just a 1:50,000 map and a lensatic compass.

  • CdtGillies

    Thanks TJK
    Great to hear that I’m not the only one just using map and compass.

  • TacZen

    Great Intro Artical… Thanks ITS!
    Just thought I’d add this only because this is something i see SO commonly…

    By far most common mistake I see in Navigation in is the use of Grid Reference Systems (UTM, MGRS…).
    If you are using a Latitude/Longitude system (not a Grid Reference System), then you’ll be fine, the Lat/Long system is a “Point” system… that is, if you plot a latitude and plot a longitude, where they cross / intersect is the location (“Point”) you are referring to. Also, if you are using an actually “Point” on the map (a hilltop, building, intersection etc… then use that Point. but, if you are using a Grid reference sytem (those “grid Lines” with assigned numbers: Eastings / Northings…)then please take note…
    A “Grid” system is just that, it is a GRID, not a POINT. That is, if you plot your “Northern/Southern” Grid line, then your “Eastern/Western” Grid line, where they cross / intersect is NOT a point. The Point created by the intersection is the lower left corner of a Grid (Box) of which, is where the location you are referencing is located within.
    The size of Grid (Box) depends how many numerical are provided: a 4 digit grid (“12/34”) giving you a 1,000m Box, a 6 digit grid (“123/456”) giving you a 100m Box, an 8 digit grid (“1234/5678”) giving you a 10m Box and 10 digit Grid giving you a 1m Box (which by that time is essentially a “Point” anyway).
    The mistakes I see:
    ●Mistake: Just plotting the Grid as a point, or plotting the Grid point then making a circle around (a 1,000m circle if 4 digits, 100m circle if 6 digits etc…). This is wrong. If you do this, you will be wondering around with in a circle ¾ of which aren’t in the Box you should be looking in, AND the upper right of the box you should be looking in not being covering.
    *True story, while on a SAR team, we had a Border patrol agent call in the location of body remains, he plotted the location and continued his assignment. We got there, my team leader plotted the “Grid” as a “Point”, we then went to this “Point” and began the search. Problem… the Grid (the BOX) had a stream bed going through it. When I pointed out that the remains main be on the other side of the stream bed, I was informed No, the “Grid” is on this side of the Stream Bed (it was of course, on the other side…. Still within the same Grid/Box).
    ●Mistake: When plotting one grid to another (as in drawing a line from one location to another to get your azimuth / direction / bearing…) using this “Point” (the lower left corner of the grid) to draw from. This causes you to always be to the lower left of the 2 points you are referencing. If for example you are getting the Azimuth from one stick in the ground to another… these sticks can be anywhere within the Grids (Boxes) given. They may well be in the upper right corner of the box, or one in it’s upper right and the other in it’s lower left etc… Best solution; use the MIDDLE of the Grid / Box as your “Points” to draw your lines. This will give you the least margin of error possible. (of course, if you have an actual point / spot on the map such as a hilltop and building etc… use the actaul point when possible).
    ●Mistake: “Rounding off”, as in, A “point” on the map is closer to this Grid Line “12” than that Grid line “13” so I’ll use the one it is closer too. If a location is in a box, it is in THAT box and no other, if you round off to the closest line, you just might put it in a box it is not in at all. While you as the plotter may not be concerned, I as the one given a point to go find am not looking in a Box for something that isn’t there and not looking in the box where it is not.
    More often than not, Navigation isn’t so precise, if you are looking for a hilltop, a few hundred meters may not make a difference because you will know when you are on the hilltop. But if you are plotting a precise location a navigation course stick/point, a body (SAR teams), a clue (LEOs), or just want the most accurate plot you can get (Military call for fire), then this CAN be crucial, not to mention avoiding frustration on all those Land Navigation courses where you just know you did everything right (ever notice the trend that what you are looking for is usually North-East of the “Point” you thought it should be… this is why).

    • TacZen

      Just to clearify, this is for when stickly useing a provided Grid such as “UTM 123-456”. If you are given a grid and can terrain associate a prominate terrain feature (both on the map and on the ground), you can plot that feature (Building, hilltop etc…) and use that “Point”.

Do you have what you need to prevail?

Shop the ITS Store for exclusive merchandise, equipment and hard to find tactical gear.

Do you have what you need to prevail? Tap the button below to see what you’re missing.