Basic Land Navigation

 

Tools of the Trade.

Tools of the Trade.

In this world of GPS navigation where you simply plug-in a set of coordinates and go where the little gizmo tells you to, basic land navigation skills have fallen by the wayside in many cases.

What if  when the SHTF the government takes the civilian GPS system off-line? It has happened in the past and will probably happen again in the future. What if they decide to put a 100 meter offset back on the system for civilian GPS receivers again? What if you find yourself in a survival situation and the batteries on your high-speed, low drag über expensive GPS receiver go dead?

Do you have the basic skills necessary to read a map? How about plan a route and move from point A to point B using nothing but a map and compass? Can you find your location with only a map and compass using terrain association?

If you can’t then read on! If you can then you are at least 10 steps ahead of the guy (or girl) who can’t!

Topo Maps
1:25,000 Scale Topo Map printed using National Geographic TOPO! mapping program.

1:25,000 Scale Topo Map printed using National Geographic TOPO! mapping program.

The simplest definition of a topo map is that it is a graphic representation of a selected area using contour lines to show variations in elevation and various symbols to show both natural and man-made features.

Topo maps come in different sizes, or scales, with each size showing more or less detail. For example a topo map with a scale of 1:100,000 will show the largest area but the least amount of detail. A map of 1:25,000 scale will show a smaller area but have greater detail. Maps with a scale of 1:50,000 (Military Topo Maps) to 1:24,000 are the ones best suited to land navigation.

Parts of a Topo Map

Most topo maps have a legend, scale, sheet number, grid lines, grid numbers, and North Declination arrows.

The Legend on a topo map tells you what the various lines and colors on the map mean.

The map's Legend tells you what the different lines and colors on the map mean.

The map’s Legend tells you what the different lines and colors on the map mean.

Map Legend

Map Legend

Map Legend

Map Legend

Map Legend

Map Legend

The Scale allows you to measure distances on the map.

The Scale allows you to measure distances on the map.

The Scale allows you to measure distances on the map.

The Sheet Number is used to tell you what part of the Quadrangle the Map belongs to.

The Sheet Number tells you what part of the Quadrangle the map covers.

The Sheet Number tells you what part of the Quadrangle the map covers.

Grid Lines break the map up into 1000 meter (1km) squares.

Grid Lines break the map up into 1000 meter (1km) squares.

Grid Lines break the map up into 1000 meter (1km) squares.

Grid Numbers allow you to find your position on the map and relay that position to others using Grid Coordinates.

Grid Numbers allow you to find your position on the map and relay that position to others using Grid Coordinates.

Grid Numbers allow you to find your position on the map and relay that position to others using Grid Coordinates.

The North Declination Lines tell you the offset between True North and Magnetic North. By using the North Declination Lines and a compass you can orient your map so that what you see on the map is the same as what you see around you.

The North Declination Line shows you the offset between True North and Magnetic North and allows you to orient your map correctly.

The North Declination Line shows you the offset between True North and Magnetic North and allows you to orient your map correctly.

Some topo maps have more information than I mentioned and some have less, it all depends on whether the map you are using was produced by the USGS or a mapping program like TOPO!

TOPO! does not add a legend to the maps you print, I added the legend on the maps used in this article to show you what they look like.

Orienting Your Map

Use your compass and the Declination Line in the LOWER RIGHT HAND CORNER of your map to orient your map to North.

Line the edge of your compass up with the Magnetic North Declination Line slowly turn the map until the North Seeking Arrow of your compass and the Magnetic North Declination Line are pointing in the same direction.

Orienting your map to Magnetic North using the Declination Lines.

Orienting your map to Magnetic North using the Declination Lines.

Finding Your Grid Coordinates

If you have a good idea of where you are you can get a more exact fix on your location by finding your grid coordinates. All topo maps have grid numbers listed on the top, bottom, and both sides. To find your grid coordinates you simply find the numbered line to the RIGHT of the grid you are square in.

To find the 1km Grid Square you are in first read RIGHT.

To find the 1km Grid Square you are in first read RIGHT.

Then you find the numbered line on the BOTTOM of the grid square you are in and you can get the four (4) digit grid coordinate which will give you the 1km square area you are in.

Next you will read the Grid Coordinate for the BOTTOM line.

Next you will read the Grid Coordinate for the BOTTOM line.

In this example the 4 digit grid coordinate is 6104, you now know the 1000 meter (1km) area you are in.

Remember you read the map RIGHT AND UP.

To get a more exact fix on your location you first break the two (2) sides (from right to left and bottom to top) into ten (10) equal parts each.

Next you will read the Grid Coordinate for the BOTTOM line.

Next you will read the Grid Coordinate for the BOTTOM line.

To get the next set of numbers for your coordinates you first go from the right and figure out which of the ten (10) parts you are in. In this case the first 3 digits of your Grid Coordinates would be 614.

Then do the same from the bottom up.

The next number in the Grid Coordinate comes from the imaginary line that runs up and down on the right side.

The next number in the Grid Coordinate comes from the imaginary line that runs up and down on the right side.

In this case the Grid Coordinate would be 046.

Where the lines cross is the six (6) digit grid coordinate, 614046 in this case, which will give you your location within 100 meters.

To get your coordinates within ten (10) meters of your location you divide each of those ten (10) squares you mentally created in half, you would use either five (5) for half way between those lines or zero (0) for directly on a line.

Land Nav 8Digit Up

Example of 8 Digit Grid Coordinate

Where the lines cross in this example, the 8 Digit Grid Coordinate would be 61450455 which is within 10 meters of your exact location.

It takes practice, lots of practice to “eyeball” an eight (8) digit grid coordinate but it can be done.

They do sell protractor’s that will make the job easier.

Example of a Protractor used for land navigation.

Example of a Protractor used for land navigation.

Being able to find your location on the map by finding your grid coordinates will help you find not only where you are, but how far you are from your destination, what obstacles are in your way, and how to plan the best route(s) to take.

Resection

If you don’t have an idea of where you are or you have become lost don’t worry, you can still find out where you are on the map by using a technique called RESECTION.

To find your location using resection make sure your map is oriented to Magnetic North and then look to your right for a prominent terrain feature such as a hill-top, mountain top, lake, or river. Using your compass “shoot an azimuth” to that terrain feature, then find that feature on the map. Lay your compass on the map so that the terrain feature you just shot is at the same azimuth and using the edge of your compass draw a line backwards to your point of view.

Aligning the compass on the map so the edge goes through the terrain feature you just shot your azimuth too.

Aligning the compass on the map so the edge goes through the terrain feature you just shot your azimuth too.

Line drawn backwards from terrain feature.

Line drawn backwards from terrain feature.

Next look to your left for another prominent terrain feature that you can see, shoot an azimuth to it, and lay your compass on the map so the edge passes through the terrain feature along the same azimuth.

Aligning the compass on the map so the edge goes through the terrain feature you just shot your azimuth too.

Aligning the compass on the map so the edge goes through the terrain feature you just shot your azimuth too.

Where the two lines cross is your location on the map.

Where the two line intersect is your location on the map.

Where the two-line intersect is your location on the map.

Now that you have your location on the map by using RESECTION it is a simple matter to find the grid coordinates for that location.

Using a protractor to find  8 digit grid coordinates.

Using a protractor to find 8 digit grid coordinates.

The 8 digit grid coordinate to the point the lines intersect.

The 8 digit grid coordinate to the point the lines intersect.

You now know your location on the map to within 10 meters. You can pass those coordinates on to other members of your party or rescuers, you can also use the information to plan the route for your next move.

Being able to navigate is an essential skill to have. That GPS unit is great, clear up until the batteries go dead or the system is shut down. If you have all of your waypoints or the locations of your caches stored in your GPS and that is your sole means of finding them you are asking for trouble! Having the grid coordinates of your caches, camp areas, etc, and knowing how to navigate using nothing but a map and compass you can still locate those supplies or that safe area when that fancy GPS stops working.

I look forward to seeing your comments and as always, Train to Survive!

Tom

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