What is the use of protractor in topographic mapping?
The three primary functions of protractors for map reading are plotting points on a map, measuring distances and determining azimuths (angles). They are helpful tools for navigating on air, land, or sea.
How do you calculate land navigation?
The first thing you must do is to set up a 100-meter course on flat terrain. Walk it three times and every time your left foot hits the ground, count it. Take the total number of steps you’ve walked and divide by three. That is your baseline pace count.
What are the three land navigation methods?
There are three base directions or azimuths: true, grid, and magnetic. The Army uses azimuths to express direction. Direction is determined from your start point, or where you are, outward toward your desired destination, or your intended target.
How do you do a land nav with a protractor?
Place your protractor on your map. In the middle of the protractor, you’ll see a little hole. Place that directly over your first plot. Make sure 0° is in line with north on your map.
What is the use of protractor?
protractor, any of a group of instruments used to construct and measure plane angles. The simplest protractor comprises a semicircular disk graduated in degrees—from 0° to 180°. It is an ancient device that was already in use during the 13th century.
What is declination in land navigation?
Declination is the angular difference between any two norths. If you have a map and a compass, the one of most interest to you will be between magnetic and grid north. The declination diagram (Figure 6-8) shows the angular relationship, represented by prongs, among grid, magnetic, and true norths.
What are the four main points of direction called?
North, east, south, and west are the four cardinal directions, often marked by the initials N, E, S, and W.
How do you use a protractor on a map?
In the middle of the protractor, you’ll see a little hole. Place that directly over your first plot. Make sure 0° is in line with north on your map. Look where the line you just drew on your map lines up on your protractor hashmarks. In this case, it hits the 165° mark.
How do you find the azimuth of a protractor?
Keeping the index at this point, line up the 0-to-180-degree line, or base line, of the protractor on the vertical, north-south grid line. 3. Follow your line outward to the degree scale of your protractor. Read the value of the angle from the protractor. This is your grid azimuth from point A to point B expressed in degrees.
How can I get an accurate reading with the protractor?
To obtain an accurate reading with the protractor (to the nearest degree or 10 mils), there are two techniques to check that the base line of the protractor is parallel to a north-south grid line.
Can you use a compass as a protractor?
We could use our compass as a protractor, but we’ll just use our military protractor because, well, it’s a protractor. An easy way to do it is to simply draw a line from your first plot through the plot that you’re measuring a bearing on, like so: