1. Leading Cadet Training
Basic Navigation
Leading Cadet Training
Basic Navigation
Map and Compass
Lecture 1

2. Basic Navigation Basic navigation is –
Knowing where you are on the map.
Knowing where you want to get to.
Finding the best route to get there.
Good navigation is a combination of:
Good Map Reading Skills.
Good Compass Work.
Remember lines of Latitude and Longitude
from your First Class Training ?

3. True or Grid North ? Lines of Latitude get closer
as they approach the North and South Poles.
Grid Lines differ in that they cover a flat surface
(i.e. the Map)
Because of this, Grid Lines don’t actually point
to the North Pole (True North)
Instead they are said to point to an
imaginary point called
Grid North

4. Magnetic North The Earth has its own magnetic field,
so a free moving needle aligns itself with this field.
This needle will always point in a north/south direction.
UNFORTUNATELY
the magnetic north pole
does not coincide with
the geographical north pole
(true north).

5. Magnetic North Magnetic North is in Canada.
In the UK Grid North is about 5o East of True North.
The other problem is,
Magnetic North changes its position over time ! UK
Grid North
True North
Magnetic North

6. So when navigating on a map we use
Magnetic North
So when navigating on a map we use
Grid North

7. Magnetic Variation Magnetic Variation is different across the world.
In some areas it is east of true north.
So Magnetic Variation must always
be allowed for when using
a map and compass for navigating.
To help, magnetic variation is always
displayed on the bottom of an OS Map.
Magnetic
North UK
Grid North
True
Magnetic
Variation

8. Magnetic Variation Because all compass references are made to either
Grid North or Magnetic North,
the angular difference between
these 2 north's must be known.
This angular difference is called
the Grid Magnetic Angle (GMA)
The GMA is displayed on every OS Map
in the centre of the top margin.
Magnetic
North UK
Grid North
True
Magnetic
Variation
Grid-Magnetic
Angle

9. Summary True North and south are at the geographical poles.
Grid North is the direction to which
all Ordnance Survey Maps are oriented.
We take our map bearings using Grid North.
Magnetic North is the direction
a compass points to,
and in the UK it is located approximately
5º West of Grid North.

10. Orientate Your Map Hill Woods Island Church River
Align your map with your surroundings,
using identifiable features.
Hill
Woods
Island
Church
River

11. Align your map with your surroundings,
Orientate Your Map
Align your map with your surroundings,
Stream
junction
Shoulder on a
steep slope
You are
here
Old walled
enclosure
Re-entrant
at base of slope

12. Orientate Your Map If you cannot set the map using observable features
Set the GMA against the
direction of travel arrow
of your Compass.
Put the compass on the map
and align the North-South
grid lines.
Turn map & compass
TOGETHER
until the needle falls
inside the orienting arrow –
red end pointing North.
If you cannot set the map
using observable features
you can set it with your compass.

13. Finding North If you find it difficult to set your map using
features on the ground,
it may help to know where North is.
Without a compass however,
determining North is a bit tricky.
You can get a rough idea of where North is
by using one of the following methods…..

14. Finding North 1. The Pole Star
In the northern hemisphere the North Pole
is indicated by the position of the Pole Star.
First find the Great Bear or Plough.
Find the two ‘pointer’ stars
and follow them for
a distance of four times
their separation.
And there you find the Pole Star

15. Finding North 2. Using a Watch If you can see the Sun,
hold your watch with the hour hand pointing at the sun.
Half the angle between
the 12 o’clock position and
the hour hand points South.
If you have a Digital watch,
draw a diagram showing the correct time,
and use that instead.
Due South.

16. Finding North 3. The Shadow Method Place a stick in the ground
and mark the end of its shadow.
Wait for 10 to 15 minutes,
and then,
Mark the end of the new shadow.
A line between the marks
runs roughly west to east.
East
West

17. Check of Understanding
What is navigation all about?
Checking your position against GPS
Knowing where you are on a map
Finding your latitude and longitude
Establishing your height above sea level

18. Check of Understanding
The difference between true north and grid north
arises because . . .
Latitude and longitude lines
do not match grid lines
Grid lines get closer together
near the Earths poles
Latitude and longitude lines
match grid lines exactly
Lines of latitude are not parallel

19. Check of Understanding
Which north changes position slightly
over time?
Magnetic North
True North
Geographic North
Grid North

20. Check of Understanding
Which of these symbols represents magnetic north? W X Y Z

21. Check of Understanding
Which of these statements about
the direction of magnetic north is true?
It is the same as true north
It is the same as both
true north and grid north
It differs from both
grid north and true north
It is the same as grid north

22. Check of Understanding
Correctly orientating your map will help you . . .
Read the contour numbers more easily
Measure distances more easily
Read place names more easily
Find your location more easily

23. Check of Understanding
Which of the following
is not a method for determining north
without a compass?
Finding the wind direction
Finding the Pole Star
Using a watch and the sun
Using shadows and a stick

24. Check of Understanding
From the diagram,
which letter indicates the correct position
of the Pole Star? W X Y Z

25. Check of Understanding
From the diagram,
if a shadow moves from position 1 to position 2
which arrow points to the north? W X Y Z

26. Check of Understanding
If you hold your watch as in the diagram,
which arrow points to the north? E F G H

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