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The CompassThe Compass&&
Taking a Taking a BearingBearing
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The CompassThe Compass
►Silva is the most popular compass for Silva is the most popular compass for hillwalkinghillwalking
►These are the four most common typesThese are the four most common types
Silva Type Silva Type 77
Silva Type 4Silva Type 4
Silva Type Silva Type 33
Silva Type Silva Type 1515
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Parts of the CompassParts of the Compass
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Taking a BearingTaking a Bearing
Before we can take a bearing, Before we can take a bearing, we must know 2 very important we must know 2 very important
pieces of information,pieces of information,
Where we areWhere we are&&
Where are we Where are we goinggoing
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Taking a Bearing – Step 1Taking a Bearing – Step 1
Place the compass on the Place the compass on the map so that either of the map so that either of the
edges (or one of the edges (or one of the long lines) of the base long lines) of the base plate is touching both plate is touching both your starting point and your starting point and
finishing pointfinishing point
Make sure that the Make sure that the ‘Direction of Travel ‘Direction of Travel
Arrow’ is pointing in the Arrow’ is pointing in the direction you are direction you are
travellingtravelling
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Taking a Bearing – Step 2Taking a Bearing – Step 2
Hold the ‘Base Plate’ in Hold the ‘Base Plate’ in position on the map and position on the map and
turn the ‘Compass turn the ‘Compass Housing’ so that the Housing’ so that the
‘Orienting Arrow of the ‘Orienting Arrow of the Housing’ is pointing to Housing’ is pointing to North on the map (The North on the map (The lines inside the housing lines inside the housing should be parallel with should be parallel with
the grid lines on the map)the grid lines on the map)
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Taking a Bearing – Step Taking a Bearing – Step 2a2a
Double check that the Double check that the ‘Base Plate’ is still ‘Base Plate’ is still
lined up on your two lined up on your two pointspoints
Lift the compass off the Lift the compass off the mapmap
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Taking a Bearing – Step 3Taking a Bearing – Step 3
Read the bearing on Read the bearing on the rim of the the rim of the
housing – This is your housing – This is your GRID BEARINGGRID BEARING
Add your magnetic Add your magnetic variation to this variation to this
number (and turn the number (and turn the housing to the new housing to the new number) – This is number) – This is your your MAGNETIC MAGNETIC
BEARINGBEARING
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Taking a Bearing – Step 4Taking a Bearing – Step 4
Hold the compass in Hold the compass in front of you with the front of you with the ‘Direction of Travel ‘Direction of Travel
Arrow’ pointing Arrow’ pointing directly away from youdirectly away from youTurn your whole body Turn your whole body
until the north end of until the north end of the needle is in line the needle is in line with the ‘Orienting with the ‘Orienting
Arrow of the Housing’Arrow of the Housing’The ‘Direction of Travel The ‘Direction of Travel
Arrow’ is now pointing Arrow’ is now pointing towards your objectivetowards your objective
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Following a BearingFollowing a Bearing
Once you have your magnetic Once you have your magnetic bearing, and the compass is bearing, and the compass is
pointing to your objective, you pointing to your objective, you need to start walkingneed to start walking
Do not walk and look at the Do not walk and look at the compass at the same timecompass at the same time
- It’s easy to veer off your bearing- It’s easy to veer off your bearing- You can’t see what’s in front and You can’t see what’s in front and
around youaround you
Find an intermediate point that is Find an intermediate point that is on your bearing, put your on your bearing, put your
compass down and walk to this compass down and walk to this point, and repeat this until you point, and repeat this until you
get to your objectiveget to your objective
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NorthNorthThere are 3 different types of NorthThere are 3 different types of North
► TRUE NORTHTRUE NORTH - The North Pole- The North Pole►GRID NORTHGRID NORTH - Where the grid on your map is - Where the grid on your map is
pointing. pointing. Since grid lines on the map Since grid lines on the map are all are all parallel, they never meet in parallel, they never meet in one point. one point. Therefore each grid Therefore each grid line is pointing to a line is pointing to a slightly different North slightly different North
►MAGNETIC NORTH MAGNETIC NORTH - Where the magnetic needle points.- Where the magnetic needle points. This is not at the North Pole - it is in This is not at the North Pole - it is in
fact in Canada somewhere fact in Canada somewhere north of north of Hudson Bay. Hudson Bay.
To complicate matters this point To complicate matters this point moves position (This movement is moves position (This movement is
predictable however and predictable however and easy to easy to calculate). calculate).
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As walkers we take our bearing from the grid on the As walkers we take our bearing from the grid on the map.map.
We need to convert this to a magnetic bearing –We need to convert this to a magnetic bearing – where the compass actually points.where the compass actually points.
This is our This is our MAGNETIC VARIATIONMAGNETIC VARIATION..
Due to every grid line pointing to a slightly different Due to every grid line pointing to a slightly different north, this variation is different on every map.north, this variation is different on every map.
Therefore instead of having a number in our head as Therefore instead of having a number in our head as a magnetic variation, you need to know how to work a magnetic variation, you need to know how to work out the variation on the map that you are usingout the variation on the map that you are using
Somewhere in the legend of the map it will tell you Somewhere in the legend of the map it will tell you how to work this outhow to work this out
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North PointAt the mid point of the eastern edge of
thisSheet True North is 01˚ 09’E of Grid
North.At the mid-point of the western edge
of thisSheet True North is 01˚ 36’E of Grid
North.At the centre of this map Magnetic
North is06˚ 56’ West of Grid North (1995).Annual decrease 09.4’.
Kerry Sheet 78 Kerry Sheet 78 Achill Sheet 30 Achill Sheet 30 North PointAt the mid point of the eastern edge of
thisSheet True North is 01˚ 20’E of Grid
North.At the mid-point of the western edge
of thisSheet True North is 01˚ 49’E of Grid
North.At the centre of this map Magnetic
North is07˚ 16’ West of Grid North (1995).Annual decrease 09.9’.
North WalesNorth WalesNorth PointsAt the centre of the E and W sheets true north is 1˚27’ and 1˚42’ east of grid north respectively. Magnetic north is estimated at 4˚ west of gridnorth for 1999 decreasing by about ½˚ in four years
As walkers we are As walkers we are only interested in only interested in the last sentence, the last sentence,
which is the which is the relationship relationship
between grid and between grid and magnetic northmagnetic north
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