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Rhys Rhys Llywelyn Llywelyn The Compass The Compass & & Taking a Taking a Bearing Bearing

The Compass & Taking a Bearing

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The Compass & Taking a Bearing. The Compass. Silva is the most popular compass for hillwalking These are the four most common types. Silva Type 7. Silva Type 3. Silva Type 4. Silva Type 15. Parts of the Compass. Taking a Bearing. - PowerPoint PPT Presentation

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Page 1: The Compass & Taking a Bearing

Rhys Rhys LlywelynLlywelyn

The CompassThe Compass&&

Taking a Taking a BearingBearing

Page 2: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 3: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

Parts of the CompassParts of the Compass

Page 4: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 5: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 6: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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)

Page 7: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 8: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 9: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 10: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 11: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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).

Page 12: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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

Page 13: The Compass & Taking a Bearing

Rhys LlywelynRhys Llywelyn

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