Find Your Position (Triangulation)
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What you will learn
- 1Choose landmarks you can see and also find on the map
- 2Take a bearing to a landmark with a compass
- 3Work out a back bearing by adding or subtracting 180
- 4Draw back-bearing lines on the map to find where you are
- 5Explain why landmarks spread far apart give a better fix
Mini Lesson
In Grade 5 you used a map and compass to walk on a bearing. But what if you are not sure exactly where you are on the map? Navigators use a trick called triangulation. You take bearings to landmarks you can see, then draw lines back from them on the map. Where the lines cross is roughly where you are standing. You practice this with your grown-up, on a trail you know.
🌿 The Wild Way (pick your landmarks)
- ORIENT THE MAP: first set the map with your compass so it matches the land, just like in Grade 5.
- SEE IT AND FIND IT: choose two or three landmarks you can see clearly AND find on the map, like a peak, a lake, a tower or a bridge.
- SPREAD THEM OUT: pick landmarks in very different directions. Lines that cross at a wide angle give a better fix than lines that are nearly side by side.
- TWO NORTHS: in many places compass north and map north are slightly different. Your grown-up shows you how to adjust for it where you live.
🌿 The Wild Way (bearing, back bearing, line, cross)
- TAKE A BEARING: point the direction-of-travel arrow at the landmark. Turn the dial until the orienting arrow sits under the red needle, then read the number.
- BACK BEARING: this is the direction from the landmark back to you. If the bearing is under 180, add 180. If it is 180 or more, subtract 180.
- DRAW THE LINE: set the dial to the back bearing. Put a corner of the baseplate on the landmark on the map and turn the whole compass until the orienting lines match the map’s north lines. Draw a light pencil line along the edge, in the direction of the arrow.
- REPEAT: do the same for the second landmark, and a third if you can.
- WHERE THEY CROSS: the lines cross roughly where you are. Three lines often make a small triangle, and you are somewhere inside it.
- CHECK IT: does the spot match the land? Look for the stream, hill or trail you can see near you.
Practice triangulation only with your grown-up, on a trail or in a park you know. Never leave the trail on your own to look for a landmark. If you are ever unsure where you are, stop, stay together and let the adult decide what to do.
Words to know
triangulation
Finding where you are by drawing lines from two or three known landmarks on a map.
e.g. We used triangulation with a peak and a tower.
landmark
Something easy to see that you can also find on the map.
e.g. The lake was a good landmark because it was on the map.
bearing
A direction measured in degrees from north, from 0 to 360.
e.g. The bearing to the tower was 60 degrees.
back bearing
The opposite direction of a bearing, found by adding or subtracting 180.
e.g. A bearing of 300 has a back bearing of 120.
orient
To turn the map so it matches the land around you.
e.g. We oriented the map before taking any bearings.
fix
The spot on the map where your lines cross, showing roughly where you are.
e.g. Three landmarks gave us a good fix.
🧠 Survivor’s Trick: check your back bearing with a quick sense test. A bearing and its back bearing always point in opposite directions. If the landmark is to the northeast of you, you must be to the southwest of the landmark, so your back bearing should point southwest.
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