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This section aims to provide a brief overview of the skills used when planning and walking routes. Much of a Scout's experience in this area will be gained during the weekly meetings and the content here is included in the orienteering badge.
 

The Compass
 

A basic magnetic compass consists of a transparent rectangular base plate including a direction of travel line and a needle. The needle is protected by a circular rotating housing that is filled with a fluid that reduces vibrations of the needle.

 

Below the needle you have an orienting arrow and a set of parallel merdian lines. A dial around the circumference of the housing is divided just as cartographers divide the earth, into 360°.

 

You also have the letters N, S, E AND W for North, South, East and West:

 

  • North is 0° (360°)
  • East is 90°
  • South is 180°
  • West is 270°
Remember bearings are always given with three figures, so even if the bearing is 70°, you write down 070° on route card.
 
If you are given a St. Columba's compass for use during an evening or expedition, make sure and look after it and keep it in a safe place. They are expensive, very temperamental and can break easily.
 

Taking a Bearing

 

Taking a bearing is very important if you want to walk in the right direction. Below are a few steps that should help you to remember how to take a bearing from a map and walk on it. Set your compass on the map and follow these stages:

  1. Firstly, put your compass on the map so that the edge of the compass is at a point, A. The edge you must be using is either longer side (both of these sides are parallel to the direction of travel line and arrow). Next, move the compass so that another point, B, lies along the same edge. Ensure the direction of travel arrow is pointing from A to B.
  2. Keep the compass steady on the map. While you have the edge of the compass carefully aligned from A to B, rotate the compass housing/bezel so that the orienting lines in the compass housing (that turn with your rotations) are aligned exactly with the blue lines going north-south (meridian lines) on the map. Ensure the middle red orientation arrow points North.
  3. Now lift the compass off the map. To improve accuracy there is usually a small white line visible beneath the bezel markings which is continuous with the direction of travel arrow. Therefore, read off exactly where this line lies.
  4. Add the local magnetic variations which you will find on the key or top of the map (usually a few degrees). This gives you a bearing from A to B which you can then follow immediately or write down on a route card for reference during an expedition.
To follow a bearing:
  1. If not already done, rotate the compass bezel so that the desired bearing is aligned with the direction of travel arrow i.e. the small white line is directly beneth the desired bearing.
  2. Turn your body with the compass in front of you so that the red magnetic needle aligns with the orienting lines and matches with the North orienting arrow.
  3. The direction the direction of travel arrow on the compass now points is the direction you should travel!
Note: The more accurate you can be when taking a bearing and when following it, the closer you will be to your destination.
 

The Map

Understanding Height and Contours

 
Height on maps is shown in three ways:
  1. Spot Heights: These are points marked on maps where the exact height has been accurately surveyed. These are shown as dots with the height marked beside it.
  2. Trig. Points: These are points marked on a map where the exact height has been accurately surveyed. These usually show the highest point in an area and are shown as a dot inside a triangle with the height marked beside it.
  3. Contour Lines: These are imaginary lines joining places with the same height above sea level. When planning a route it is important to take into account the gradient of any hills. Contour lines show you easily how steep a hill is - the closer the lines the steeper the hill.

Four-figure Grid References

These are given as four numbers. The first two digits of the four refer to the vertical lines on a map and the second two digits refer to the horizontal lines on a map. All of the blue reference lines are marked with numbers such as 12, 29, 31 etc at the sides. Therefore, if you are given the four-figure grid reference 2514 you simply go across to vertical line 25. Then, find where this line intersects with horizontal line 14. The box outlined to the right and above this intersection point is the area to which the four-figure grid reference refers to. This may be as large as a square kilometre.
 
Six-figure Grid References
 
These are given as six numbers, are more accurate and almost as simple to use. Indeed, you may find it easiest to begin by ignoring the third and sixth digits to create a four-figure grid reference. The first three digits of the six refer to the vertical lines on a map and the second three digits refer to the horizontal lines on a map. Although there are no blue lines to tell you where the third figure is on the map, each number is a tenth further into the square before the next line. This means that if the first three figures in a six-figure grid reference were 275, you want to find the point half-way between the 27th and 28th vertical (meridian) lines.
So, if you are given the six-figure grid reference 327113 you simply go across to vertical line 32 and go 7 tenths towards line 33. Then, go down to horizontal line 11 and go 3 tenths towards line 12.
 
Note: If you know where you are on a map and need to relay your location you work backwards to obtain a six-figure grid reference. This can be particularly useful in emergency situations to get assistance to your exact position easily.