A compass is used to find magnetic north orientate yourself and you your map to the ground, and navigate on a bearing in your desired direction of travel. It is an invaluable tool for anyone travelling in the wilderness, hiking in the mountains or anywhere that you cannot use a GPS. So, how do you use a compass?
The use of a map and compass is a divisive one in hiking communities in the UK. With good GPS and 4/5G signal in many areas, some argue that a map and compass is now surplus to requirements. Personally, I will always carry and map and compass of the place I am hiking in. If you develop a fault with the GPS unit, or lose phone signal – something that happens often in Scotland, you will, most likely, get lost. In itself not a problem, but it is easily done and can lead to trouble.
Below, we will look at the different parts of the compass and how it can be used to aid in your navigation.
The Parts Of A Compass
- Base Plate – this is the main square part of the compass that has a lot of useful features printed/etched upon it. The image above is of a Silva Compass, which is what I use. It generally has rulers, romers and scales that you can use to measure distances on your map. It sometimes has a magnifying glass too.
- Direction of Travel Arrow – this is found at the top of the compass and is used when working out bearings and measuring route legs when preparing your route card in advance of your walk. More about that here.
- Compass Housing – onto the round moveable part of the compass now, this is the cover that houses the magnetic needle within it.
- Degree Dial – this is the rotating part of the compass, reading from 0 to 360 degrees on a civilian compass.
- Orienting lines and Orienting Arrow – printed inside the compass housing, these lines are used to align your compass to the map. This is called orientating your map – which I have written about here.
- Compass Needle – the magnetic part of the compass that moves freely pointing towards magnetic north.
Orientating Yourself to North
The easiest thing to do with a compass it to use it to turn yourself in a known direction. In this example I will use north as the direction in which you want to travel.
First, take your compass and hold it flat in front of you with the direction of travel arrow (the larger one printed onto the baseplate) facing directly away from you. It is important that the compass is fat when you do this. If the compass is angled, this can affect the turning of the compass needle, giving you an inaccurate reading.
Whilst you are holding the compass flat in front of you, turn the compass housing and degree dial so that the orientation arrow points in the same direction as the direction of travel arrow, away from you. Ignore the compass needle at this point. Be sure to line up the two arrows accurately, inaccuracy will again stop you achieving the correct orientation.
Once the two arrows are aligned, keeping the compass held in front of you, turn yourself on the spot so that the magnetic compass needle falls within the orientation arrow and lines up with the direction of travel arrow. Once this is complete, you are facing north. You can now identify the different compass directions, key features you can see around you and confidently know which way you are facing.
Taking a Magnetic Bearing
Take your compass, hold it level in front of you. Point the direction of travel in the direction you want to go. I would always try and use a large feature on your route to point your compass at, rather than a generic “kind of over that way” direction”. Let’s say you are going to navigate in a straight line to a spot height that you can currently see, point the direction of travel arrow at that spot height.
Then rotate the compass housing to line up the orientation arrow with the magnetic needle inside the housing. Your compass is now set up to use on a bearing. Make sure you line up the orientation arrow with the north on the needle, not the south. This is usually matching the red end of the needle to the red arrow on the housing. Getting this wrong means you will head off 180 degrees in the wrong direction.
Take note of the reading on the compass dial under the direction of travel arrow, this is the bearing on which you will travel.
To walk on this bearing, you can set off along your direction of travel arrow, taking care to keep the magnetic needle lined up to the orientation arrow. Even if you lose sight of your objective – in this case the spot height – you can confidently continue walking knowing that you will reach your objective if you continue walking on your bearing.
Taking A Grid Bearing
This is similar to taking a magnetic bearing, except rather than taking a bearing on site of your objective, you use your map. To take a grid bearing, lay your map on a flat, dry surface and identify your location on it. The identify the point to which you want to navigate. Take your compass and lay it on your map, with the edge of the baseplate along the desired line of travel. Make sure the compass and direction of travel arrow is pointing in the right direction.
Be sure to keep your compass on this line during the next steps, hold it firmly in place. Then rotate the compass housing so that the orienting lines line up with the gridlines on the map. Again, take care with your accuracy at that stage. The reading on the degree dial in now your grid bearing.
If you are going to use this to walk on, you need to account for the Grid Magnetic Angle, which can be calculated using the key at the top of your map. Add or subtract the GMA from your grid bearing. To walk on the bearing, rotate yourself, map and compass until the magnetic needle lines up with the orientation arrow in the housing.
You can now put your map away and, taking care to keep the magnetic needle in the orientation arrow walk towards your objective.
- Retake your bearings every 1-200 metres to ensure your accuracy.
- Ensure you are as accurate as possible with your measurements and using the degree dial.
- Choose obvious landmarks like spot heights or track junctions as your leg objectives where possible.
If you follow these quick steps and practice them, you’ll be confident with your compass and navigation, avoiding the dreaded feeling of becoming lost in the hills.
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