1. Leading Cadet Training
Basic Navigation
Leading Cadet Training
The Compass
and Bearings
Lecture 2

2. The Compass Parts of a Compass Direction of Travel Arrow Rommers
1:25000
1:50000
1:63360
Metric Ruler
(cms)
Illuminating Mark
Under index.
Aside north arrow
On mag needle
Check Point Marker
Parts of a Compass
Compass Housing
Magnifying Glass
Magnetic Needle
Index
Meridian Lines x 4
Orienting Lines
North Arrow
Orienting arrow
Outer Circle = mils
Inner Circle = degrees
Imperial Ruler
(inches)
Non-slip Feet x3
Base Plate
Lanyard

3. The Compass The Compass Housing contains
a magnetic bar, called the Needle
and defines the points of the
compass on a rotating bezel.
Compass Housing
The Magnetic Needle is suspended
in liquid, enabling it to move freely,
and settle quickly when pointing North.
Magnetic Needle
The Base Plate is the mounting
for the housing and displays
a variety of information
e.g. Scale ruler.
Base Plate

4. Direction of Travel Arrow
The Compass
The Direction of Travel Arrow
indicates the direction along which
you wish to travel or take a bearing.
It is fixed in the base plate and the
sides of the base plate run
parallel to the arrow.
Direction of Travel Arrow
Index Line
The Index Line is a fixed line within
the Compass Housing and is in line
with the direction of travel arrow.
The Index Line marks the bearing
you set by rotating the bezel.

5. The Compass The Orienting, or Meridian Lines
are displayed within the rotating
Compass Housing and are designed
to be aligned parallel with the
Eastings on a map.
The lines on some compass models
are show as one half in red
to depict north.
Meridian Lines x 4
Orienting Lines

6. The Compass Nearly all compasses have a scale
along the edge of the base plate
to enable you to measure distances.
Used in conjunction with the scale
at the bottom of the map,
the compass scale enables you to
calculate the distance on the ground.
Metric Ruler
(cms)
Imperial Ruler
(inches)

7. N ? ? ? W E S The Compass NW NE SW SE NNW NNE WNW ENE WSW ESE SSW SSE
Points of a Compass N
NNW
NNE ? NW NE
WNW
ENE W E ?
WSW
ESE SW SE ?
SSW
SSE S

8. N W E S The Compass NE SW NW SE ESE WNW SSE SSW WSW NNW NNE ENE
Points of a Compass
ESE NE N S E W SW NW SE
WNW
SSE
SSW
WSW
NNW
NNE
ENE
0º & 360º
North West : 315º
45º North East
270º
90º
South West : 225º
135º South East
180º

9. Setting a Map with a Compass
The Compass
Setting a Map with a Compass
You can orientate yourself, and the map
to the ground by using this system:
Lay the compass on the map.
Line up the edge of the compass
and the compass orienting lines
with the Eastings.
Turn your body until the red end of
the needle is in line with the ‘N’
on the Housing.
You and your map are now facing North.

10. Compass Bearings Points to Note Stand clear of metal objects,
they cause the needle to deviate
and create inaccurate bearings.
Hold the compass as flat as possible
to allow the needle to move freely.
Look after your compass –
try to avoid dropping or knocking it.
Store away from other compasses
and electrical equipment.
Your compass may need replacing
if an air bubble forms in the Compass Housing.

11. Compass Bearings When working from a map we deal with Grid Bearings.
When following a compass on the ground
we work with Magnetic Bearings.
There is a simple system which enables us
to convert Grid to Mag and Mag to Grid,
The system refers to whether we add or subtract
the magnetic variation to convert the bearing.
Mag to Grid…………..GET RID
Grid to Mag……………….ADD

12. Compass Bearings Map to Ground Take a Bearing
You are at Point A and need to walk to Point B
Unfortunately,
you can’t see Point B
Place the Compass on
the Map like so:
The direction of travel arrow
should point in the direction you wish to go. B A

13. Compass Bearings Map to Ground Take a Bearing
Keeping the Base Plate static –
Turn the Compass Housing
until the Orienting Lines
are parallel with
the Eastings
And the ‘N’ is pointing
to North on your map. B A

14. Compass Bearings Map to Ground Take a Bearing
Read the Compass Bearing shown on the housing
from the Index Line
Don’t forget the difference
between Grid North
and Magnetic North.
Add this to your bearing.
(From Grid to Mag = Add)
and you have the magnetic bearing of your course.
The next step is to orientate yourself B A x

15. Compass Bearings Map to Ground Take a Bearing
Hold your Compass level and steady.
Turn until the red end of the Needle
is in line with the ‘N’ on the Housing
The Direction of Travel Arrow
is now pointing along the route
you plotted on the map,
and you are ready to travel.

16. Compass Bearings Map to Ground Back Bearings
Point the Direction of Travel arrow at the feature,
and take a normal bearing.
Turn the Compass Housing
until the Orienting Lines
are REVERSE parallel
with the Eastings
Read the bearing and subtract the GMA.
Remember – Mag to Grid = Get Rid
This is the back bearing of your feature. B A x

17. Check of Understanding
What is the purpose of liquid
in the capsule of a compass?
Allows the needle to be seen more clearly
Increases the needles sensitivity
Slows the swing of the needle
Allows the needle to settle quickly

18. Check of Understanding
When changing magnetic bearing to grid bearings
Which of the following is correct?
Mag to grid - Multiply
Mag to grid - Add
Mag to grid – Get Rid
Always an addition

19. Check of Understanding
Which of the following would be more likely to cause
magnetic deviation if close to a compass?
A cattle grid
A large tree
Aluminium tent poles
A river

20. Check of Understanding
How can a grid bearing from a map
on which the magnetic variation is westerly
be converted to a magnetic bearing?
Add the angular difference between
magnetic north and grid north
Add the angular difference between
grid north and true north
Subtract the angular difference between
magnetic north and grid north
Subtract the angular difference between
grid north and true north

21. Check of Understanding
To take a bearing on a map,
having set the compass so that the
Direction of Travel Arrow points at the feature,
what do you do next?
Turn the capsule to deduct
the grid magnetic angle
Turn the capsule so the orienting lines
are parallel to the north-south grid lines
Turn the map and compass until the needle
falls into the orienting arrow
Turn the capsule until the needle
falls into the orienting arrow

22. Check of Understanding
A line on a map is found to be 110 degrees grid.
If magnetic north is 6 degrees west of grid north,
what is the magnetic bearing of the line?
98 degrees M
104 degrees M
116 degrees M
122 degrees M

23. Leading Cadet Training
Basic Navigation
Leading Cadet Training
End of Presentation