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N.E E S.E S S.W W N.W 90 180 270 45 135 225 315 Silva Compass Parts How a Compass Works Setting the Map with a Compass 1) Twist the bezel so that the Shed ... – PowerPoint PPT presentation

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Title: to the


1
Introduction to the compass
2
45
315
N.E
N.W
90
270
E
W
S.E
S.W
135
225
S
180
3
Silva Compass Parts
4
How a Compass Works
5
Setting the Map with a Compass 1) Twist the bezel
so that the Shed is at the top.
6
2) Lay the compass along one of the North/South
gridlines pointing towards the top of the map
7
3) Rotate the map with the compass held still and
put the RED IN THE SHED. I.e. the red arrow in
the red shed, the map is now set to North!
8
Exercise Using your map and compass, set the
map to North
9
  • Taking a magnetic (Compass) Bearing
  • Point the compass direction of travel arrow
  • at the object that you wish to take the bearing
    of


10
2) Rotate the bezel until the red is in the shed
11
3) Read off the number at the direction of travel
arrow this is the magnetic bearing
12
Exercise Using your compass, Take 3 different
bearings from the room your are in, For example a
bearing to the fire extinguishers, Bearing to the
door Or a bearing to light switches
13
How to take a Grid / map bearing Lie the edge of
the compass along the place you are at and the
place you are going to, i.e. from the track to
the church with the direction of travel arrow
pointing in the intended direction
14
2) Turn the bezel until the lines inside the
bezel line up parallel with the grid lines on the
map
15
3) Read off the number, this is your grid
bearing. Note that we ignore the North arrow
when doing this, as our bearing is a grid bearing
from grid north
16
Magnetic variation The magnetic variation of the
earth changes currently it is set at 4 degrees.
This means that a bearing taken from a map will
be 4 degrees out. Likewise a real life bearing,
when transferred back to the map will also be 4
degrees out in the other direction. There is
another rule Mag to grid get rid Grid to mag
add. So if we have taken a grid bearing from a
map we have add 4 degrees And if we are taking a
bearing and transferring to the map we subtract 4
degrees.
17
Exercise You are at the summit of Conic Hill the
grid reference is 433 924, You have just come
around after being knocked out by a pigeon
dropping its lunch it is extremely foggy and you
cant see your hand in front of your face. All you
have is your map and compass and you need to get
back to your car which is at grid reference
421909. To do this you will need to walk on a
bearing from point to point What is that
bearing?
Answer 301 degrees plus 4 305
18
DIRECTION OF TRAVEL
NORTH SIGN
360 DIAL/BEZEL
MAGNETIC NEEDLE
19
True or false? 1.A compass needle is
magnetised? 2.The red part of the compass needle
points to Earth's magnetic South Pole. 3.Since
a compass is affected by magnetic fields, it
needs to be used away from iron and steel
objects. 4.The scale of the compass is 0 to 360
degrees. 5.The parallel lines inside the dial
are known as orienting lines. 6.Orienting lines
help to line up the compass with a globe. 7.The
compass needle is painted two colors (Red -
North, White - South.) 8. A bearing should be
followed by following the red shed north
indicator and not the direction line. 9. The
string can be used to measure distance from the
map 10. The bezel cannot be turned or rotated.
TRUE
FALSE
TRUE
TRUE
TRUE
TRUE
TRUE
FALSE
TRUE
FALSE
20
22.5
337.5
N.N.E
N.N.W
315
45
67.5
292.5
N.W
N.E
E.N.E
W.N.W
90
270
E
W
247.5
102
E.S.E
W.S.W
S.E
S.W
135
225
S
S.S.E
S.S.W
180
202.5
157.5
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