Home >> Hobbies >> Other Hobbies

How to Use a Military Protractor

Military protractors provide essential back-up for modern GPS devices, which can be affected by moisture, electrical interference or thick forest canopies. In conjunction with a map they can be used to find the azimuth -- direction of travel -- from one point to another. Military protractors can be either square or circular and have scales showing both degrees and mils -- a measurement of angle in which a circle is divided into 6,400 units. Most feature several calibrated cut-outs that match the most common grid square sizes used in most military maps.

Things You'll Need

Straightedge or ruler
Pencil

Instructions

- 1
  Locate the first of your two plot points on your map by identifying the correct square then using the appropriate calibrated cut-out to pinpoint the exact spot. For example, to find grid reference 7637 8941 first locate the box at the intersection of grid lines 76 and 89. Place the matching cut-out over the square and use the calibrations to find 37 on the horizontal and 41 on the vertical. Your first plot point is where where the points meet. Repeat for the second grid reference.
- 2
  Draw a line connecting the two grid references using the pencil and the straightedge. This is known as the azimuth line.
- 3
  Place the protractor on the map so the cross hairs are directly on top of the azimuth line at the point that it crosses one of the vertical grid lines on the map. Placing the protractor at this point rather than on top of one of the plots allows for far greater accuracy. Ensure the horizontal line of the cross hairs are parallel to the horizontal grid lines.
- 4
  Read the protractor scale in a clockwise direction, starting from 0, until you reach the point where the line intersects the markings. Ensure the 0 degree or 0 mil mark is at the top edge of the protractor. Make a note of the reading.

Other Hobbies