Compass features and designs

In this article you can find information about compass components, how to use it, where to use it, why it’s useful and sometimes – even necessary to find way when got lost.


 

By knowing how to use compass it can save your life and before going to long expedition you should know basic general knowledge about usage of compass.

What is compass?

Compass is navigational instrument containing a magnetized pointer/arrow which shows the direction of magnetic North and bearings from it.

Compass designs

Compasses come in many designs, but most compass features are the same as those found in an all-time classic compass like the Silva Ranger. You need to make use of some or all of the compass features for different tasks like magnifier glass or scales.

Compass features

Baseplate

 

Is a transparent plastic base with ruler measuring scale that holds all compass components together. Makes it easy to take bearing from where you are on the map and where you want to make a bearing to.

 

Compass housing or dial

 

Round screen with degrees from 0 to 360 displayed on edge and indicates North, often filled with clear fluid. This is where magnetic needle is housed. While making a bearing you can spin it to set “Red in the shed”.

Magnetic needle

Axis moving arrow held within the compass housing. Red end is magnetised and indicates North if used correctly. Needle is usually red with fluorescent to be used in the dark.

Compass lines or orienting lines

These line up with the grid lines on the map, to help with accuracy when taking bearing. Usually they are coloured red, so it’s easier to see them.

Map scales

Used to easier track or measure distance on map. Scale can measure real ground distance on the map. Usually 1:25 000, 1:50 000 and metric measurer centimetres and millimetres.

Direction of travel arrow

This points to direction you want to travel along or bearing that you want to take, both on the map and on the ground.

Magnifier glass

Makes small features like symbols or digits that is hard to read bigger and easier to see. Or in emergency you could make fire by using sun and a piece of dried grass.

Index line

This is where you read your bearing from when taking or setting it. Marks the bearing you set by rotating compass housing. It helps you to be accurate.

Orienting arrow

When making bearing, rotate the housing to point this to the North. This gives you a point to start from to begin making your bearing.

Compass features

Compass features – Silva compass with different features

Few facts about compass

  • The building of iron and steel ships made the magnetic compass useless because of all the metal on board!
  • Early compasses consisted of an iron magnetised needle attached to a piece of wood or cork that floated in a bowl of water.
  • Compass can be affected by electromagnetism.
  • Compass was invented in Asia.