Compass Basics – Locating your position accurately using three visibly identifiable features.

If you are not located on a visible linear feature such as a path, stream or ridge, but you need to know your location it’s possible to do this by using three distant visible features which are identifiable on your map.

You can use any visible features that you can identify with certainty on your map – for example, a structure, rock formation, triangulation pillar, summit or similar.

It is much more helpful if these features are also distant from one another (e.g., one to your left, one to your right, and one straight ahead, or behind you) as this will improve the accuracy of the result.

Here’s how:

  • Once you have located your three identifiable features, point your compass at the first feature and take a bearing.
  • Transfer this bearing back to your map using the method you used to locate yourself along the ridge in this post.
  • Mark a line on your map with a pencil by drawing along the edge of your baseplate.
  • Next, point your compass at the second feature and take a bearing
  • Transfer this bearing back to your map
  • Mark another line from this feature using this new bearing so that it crosses the first line that you marked.
  • Finally, point your compass at the third feature and take the bearing
  • Transfer this bearing back to your map
  • Mark a final line on your map using the third bearing so that it, too, crosses the first line that you marked, it should also cross the second line.
  • The three lines will intersect, usually leaving a small triangle (this is called a witch’s hat)
  • So long as you have taken good care in taking your bearings and transferring them back to your map, your actual location will be inside the witch’s hat. The more accurate your bearings, the smaller the witch’s hat will be. 

The technical term for this method is “resection”.

You can now set about navigating the rest of your journey using the other skills you have learned in our Basics section.