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COMPASS

The main points of the compass are:

North, South, East and West are the four main cardinal points of the compass.

The intermediate points are, North East, South East, South West and North West.

North Points

  • True North: The actual direction of the geographical North Pole.
  • Grid North: The direction of the vertical lines on a map, to all purposes Grid and True North are the same.
  • Magnetic North: the location of the Earths magnetic field and the direction the needle on a compass point to.

Know your compass and its component parts and their uses:

  • A. Romers, scales 1:50,000, 1;25,000 and 1:40,000. Theses are used when taking and plotting grid references. Just remember to use the correct scale to the map you are using.
  • B. Direction of travel arrow this mus alaways point in the direction you want to travel. When taking a grid bearing from the map the arrow must be pointing to your destination on the map.
  • C. Magnifying glass used to check the small detail on the map. plus in an emergency you could use to start a fire as long as you have sunshine.
  • D. Luminous parts for use at night. If they are dull just hold a torch on the compass and light from your torch will brighten them up.
  • E. OOOps missed that one!Should be indicating the measuring scale on that side of the compass which is in inches.
  • F. Rubber feet x three this is to prevent the compass from sliding when taking or plotting a bearing on the map.
  • G. Measuring scale in millemeters.
  • H. Stencil hole, used to mark map accuratley with a pencil.
  • I. The Index line.This is the point where you read of the bearing.
  • J. Compass housing or Bezel, A rotating dial marked in 2 degree increments.
  • K. Magnetic Needle, Remember the red half always points to the North.
  • L. Orienteering Lines, these are used when taking and plotting bearings on the map

 

Points to Remember:

Check for bubbles, if there is a bubble in a compass this can cause errors when taking bearings. If it is a small bubble place the compass inside your jacket, normally your body heat will remove a small bubble, if its a large bubble the best thing to do is place a towel on top of a radiator and lay the compass on the towel over night that should remove it, if not get rid of the compass. A large bubble will definetly push against the magnetic needle causing errors.

Avoid handling a compass when you have just applied insect repellent. Some repellent will react with the plastic and become sticky ie melting.

Check  the compass periodically or when the accuracy is in doubt to see if its functioning properly.

 

 

 

 

Prismatic Compass.

This compass in my opinion is one of the most accurate compasses you can come cross I used this type for the full 22 years of my army service.

 

 

 

OS©Crown copyright (2018)CS -36088-G0Y6Y3

OS©Crown copyright (2018)CS -36088-G0Y6Y3

OS©Crown copyright (2018)CS -36088-G0Y6Y3

 

Units of Measure.

Normall the compass you will be using will be in degress.

 However you may come across a compass marked in mils for example the Silva Compass 4 Militaire. most compasses marked in mils are used by the Military (NATO). The compass is marke in mils from 00 to 64 So North 6400 mils East 1800 mils, South 3200 mils and west 4800 mils.

Ther are 17.78 mils to 1 degree..You would think that with more increments it would be more accurate it is to an extent. At the best plotting a bearing using an hand held compass is probarly at its best 1-2 degrees.

To summarise: it is virtually impossible for a person to walk on a bearing to within 1 degree of accuarcy. i have found out with my expeirence you have to make use of other navigation techniques along with the compass. For example Attack Points, Aiming Off. The terrain you are crossing at the time will always dictate to you what you have to do.

 

 

 

 

 

 

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