Introduction: Basic Land Navigation
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. But what if the government takes the 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? Do you have the basic skills necessary to read a map? Move from point A to point B using a compass and map? Find your location with only a map and compass?
Step 1: Tools of the Trade
Basic land navigation only requires three (3) "tools". A topographic map, a compass (for this Instructable I will be using a basic orienteering compass), and a dry erase marker (if your map is laminated or sealed in plactic) or pencil.
Step 2: 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. Then you find the nubered 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. Remember you read the map RIGHT AND UP.
To get a more exact fix on your location you first break the the two (2) sides (from right to left and bottom to top) into ten (10) equal parts each. 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, then do the same from the bottom up. This will give you a six (6) digit grid coordinate, 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) square 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. It takes practice, lots of practice to "eyeball" an eight (8) digit grid coordinate but it can be done.
They do sell protractors that will make the job much easier.
Step 3: Orienting Your Map
To orient your map first lay your map on as level a surface as you can then find the North Declination line, usually located in or near the maps legend. Lay your compass on the map and line the edge of your compass up with the MAGNETIC NORTH LINE. Then simply turn your map until the North seeking arrow is pointing in the same direction as the Magnetic North Line on the map.
You can now use the compass to find a bearing to any terrain feature, road, building, grid coordinates, etc on the map.
Step 4: So You Don't Know Where You Are Huh?
When you aren't sure of your location on the map a simple, quick way to find out exactly where you are is called Resection.
First orient your map and look for a prominent terrain feature you can see to the LEFT of your location. Then find that terrain feature on your map. Place your compass on the map, with the edge of the compass running through the center of the terrrain feature and draw a line backtowards your vantage point.
Next find another terrain feature you can see to the RIGHT of your location. Find that terrain feature on the map, place your compass on the map with the edge running through the center of that terrain feature and draw another line backwards towards your vantage point.
Where the two line cross is your location. You can now get the grid coordinates to your location.
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