How to use a compass.

21 July 2014

An outdoor blog wouldn’t be an outdoor blog if it didn’t have a little section on how to use a compass. In the summer, most of the time in the Lake District, I don’t need to use my compass, but when it gets to this time of year, when the clouds come down or the wind blows up a load of snow, it’s a useful skill to have.

Here’s my simplified compass.
For what we need it for, a compass is basically three arrows and a rotating dial. The Travel Arrow is fixed at the top, the Orienting Arrow is attached to the rotating dial so you can spin it and the red end of the Magnetic Needle always points to north.

Aligning your map

When using a compass there is all sorts of scary talk like ‘following a bearing’ and ‘resectioning’ but one of the most common things to do with a compass and one of the easiest is to line up your map so you’re not walking backwards when you think you’re walking forwards (which happened to me last Saturday night at the Oktoberfest beer festival).

Here’s what to do when you’re disorientated:

1) Put your map on the ground and put your compass on the map.

2) Turn the map so the Red Magnetic Needle points to the top of the map (which is north)
That’s it, didn’t need a diagram I know, but it’s there anyway for your enjoyment. The map should now be facing in the right direction and look something like the landscape around you. You can obviously do this without a compass if you know the area and can find a couple of distinguishing features, but the compass reassures you that you’ve got it right.

Finding your destination (or taking a bearing)

If you know your current position but you can’t see your destination do this:
1) Put your map on the ground

2) Mark your current position and destination on the map and draw a line between them. You don’t really need to draw a line but it makes the reading slightly more accurate.

3) Line up the edge of the compass with the line you’ve drawn. The Travel Arrow should be in the direction of intended travel.

4) Spin the rotating dial with the Orienting Arrow attached until the Orienting Arrow points north on the map.

You’re finished with the map now.

5) Stand up, if you’re not already, hold the compass out in front of you and turn yourself until the Orienting Arrow and the Red Magnetic Needle are lined up.

6) Magically, you are now facing the right way. Keep the Orienting Arrow and Red Magnetic Needle aligned and follow the Travel Arrow to your destination.

How does that work? All you’re doing is making the map align to the physical world. The Orienting Arrow is pointing to north on the map, so when you aligned the Orienting Arrow (which is map north) with the Red Magnetic Needle (which is real north) then the Travel Arrow will point physically in the direction of travel.

There is one slight complication that you’ll know about - the difference between Magnetic North and Grid North. Don’t confuse these two norths with True North. True North is a straight line from where you are to the North Pole and it’s useless for navigation. Magnetic North is the north on your compass and Grid North is the north shown on the map.

Magnetic North changes over time and depends on the location, so for absolute accuracy you need to allow for this. Luckily, in the UK, the difference between Magnetic North and Grid North in less than 2 degrees (at the moment) which is one small division on your rotating dial. My navigation skills aren’t good enough to bother about that small adjustment, but if you want to, just rotate the wheel anticlockwise by one division, this will add 2 degrees to north.

Finding your current location

If you don’t know you’re current location, you need to be able to see three landmarks to work it out. The landmarks should be as far apart as possible.
1) Aim the Travel Arrow at the first landmark.

2) Twist the dial until the Orienting Arrow lines up the Red Magnetic Needle.

3) Take off Magnetic North/Grid North difference if necessary.

4) Place your map on the ground and align the Orienting Arrow with north on the map.

5) Find the landmark and put the edge of your compass on the landmark with the Orienting Arrow still lining up with the map north.

6) Draw a line along the compass edge all the way from the landmark to your approximate position.
7) You now need to repeat this for two other landmarks.

8) When you have three lines from three landmarks – the point at which these lines meet is your position.

Best technique if you’re lost

If you’re lost in snow or mist and there are no landmarks for you to find your current location, this is the best thing to do:

1) Align your map (as described above).

2) Take your best guess at your location.

3) Find a longish feature on the map like a river or a forest boundary or track that should be crossing your path.

4) Take a bearing (as described above) with the forest boundary or river etc. as your destination. This will be an estimate since you don’t know your exact location.

5) Using the map, double check the line you are going to follow is safe and passable on foot. If in doubt choose a longer route to the destination.

6) Follow the bearing as closely as possible.

7) Eventually you should hit the feature.

8) From there you can follow the river or forest until you find a point you can identify and can work out your exact location.

Hope that helps.

Thanks for reading.

Ian Young

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