If you've read our article "How to use a compass on a hiking trip?", you already have the basic principles for using your compass. The aim of this second piece is to teach you how to carry out compass triangulation — an operation that should help you find your bearings if you get lost while hiking, or to verify your position. It's a straightforward exercise, but it's worth knowing the principles before you find yourself in a critical situation.
In which situations should you use compass triangulation?
To carry out triangulation, you need to be able to identify prominent landmarks in the landscape (a church spire, mountain summits…) — which means you need good visibility. Forget about fog and poor visibility conditions. You'll use triangulation to confirm your position or to find out where you are if you get lost while hiking.
What tools do you need for triangulation?
You will of course need a compass, but also a map of the area you're in — and a proper map if possible. I recently saw people heading off into unfamiliar territory in a foreign country, doing a 5-hour hiking trip with nothing but a tourist leaflet featuring an imprecise map, no scale, and small illustrations giving only a rough impression of the area! It is absolutely essential to have a proper, official map — or at the very least a copy of one. Another essential tool: a pen or a pencil. I personally always have a pencil (it never runs out) attached to my compass!
How to do compass triangulation?
First and foremost, take your time. A good compass triangulation requires a little focus and patience. It's not suited to emergency situations where time is of the essence.
Start by orienting your map. We covered how to do this here. Once the map is oriented, don't move it.
Next, take the time to observe the landscape and choose clearly identifiable landmarks. You'll need at least two, but a third will give greater precision. Don't choose landmarks that are all in the same direction, as the measurement will be imprecise and highly unreliable. Pick landmarks that are well spread apart from one another.
You can choose a church spire, a peak or summit, a mobile phone mast, or a water tower. You need to be able to identify these landmarks on your map as well — and not mix them up. Don't confuse one peak with another, for example.
Take a bearing towards the first landmark: without moving the map, point the compass towards the landmark and use the straight edge of the compass as a guide to draw the line running from that landmark. The map and the magnetic needle of the compass remain oriented North throughout.
Then repeat the same operation for the second landmark, and the third if applicable.
Next, extend the lines sketched on your map. The point or area where these lines intersect is where you are!
The accuracy will never be perfect, but it will be more than sufficient to pinpoint your location correctly.
Don't hesitate to practise in a familiar area! Don't wait until you're in a critical situation to try this exercise. You can even do it from your flat or your garden, or on a hiking route you know well.
One more tip: you've done a compass triangulation and found your position — great, all is well… You reorient yourself and set off again on your way. Don't hesitate to take a little extra time, and do another triangulation (after about 20 minutes of walking, for example), trying to use a new landmark. It's a good way to reinforce your choice of direction and to "solidify" and verify your previous bearings. Do it… even if you're confident about where you are!
Compass triangulation as a way of navigating in unfamiliar terrain is a reliable method — as long as you have a reasonable grasp of it and practise it regularly. After a while, you can even do it fairly quickly in your head, without drawing a line on the map, for a quick position check. Some people will tell you: "Oh, I don't bother with that — a phone or a GPS is enough." True — except that areas with no coverage do exist, as do flat batteries. And believe me, as a rule, as if by bad luck or Murphy's Law, it's precisely when you're lost while hiking, after hours of going round in circles, that you find yourself with no battery and inevitably in an area with no signal! It's never too cautious to know how to find your bearings by your own means!
