Lecture

Leading Cadet Training

Basic Navigation

3Bearings

and Distances

RevisionWe have examined setting the map,

and working from Map to Ground.

RememberMag to Grid…..GET RIDGrid to Mag…..ADD

Now we will examine

Ground to Map

BB

AA

x

Select the feature on the ground

to which you wish to take a bearing.

Hold the Compass steady

and level.

Point the Direction of Travel Arrow at the feature,

and rotate the Housing until the red end of the needle

is in line with the ‘N’

Compass Bearings Take a Bearing

Ground to Map

Read the Compass Bearing shown on the housingfrom the Index Line

This is your Mag Bearing

which you can either travel along

or convert to a grid bearing by subtracting

the magnetic variation. (Remember Mag to Grid……Get Rid)

Compass Bearings Take a Bearing

Ground to Map

xx

Convert to a Grid Bearing.

Place the Compass on the map and keeping the bearing set on the Housing, rotate the whole Compass until the Orienting Lines are parallel to the Eastings.

The edge of the Compass should run through your position and show the bearing on the map.

x AA

Compass Bearings Take a Bearing

Ground to Map

Hold your compass level and steady.

Ensure the red end of the needle is in line with the ‘N’ on the Housing.

Follow the direction of travel arrow.

Line up the direction arrow with a physical feature (e.g. tree, pylon, tower). Use this as a reference point which is easier than following the compass every inch of the way.

Compass BearingsFollowing a Bearing

Measuring Distance

Measuring distances accurately is important because:

it both keeps you on schedule and reduces the area

of uncertainty in your position.

There are two main ways

of measuring and

estimating distance:

Timing

Pacing

Distances

Use the edge of the compassto measure the distance.

or

Use a strip of paper with 2 marks on it.

Then measure the paper against the map scale:

TimingIf you know how fast you can walk, you can work out how long it will take you to cover a known distance.

For example:

If the distance to yournext objective is 2km, and you walk at 4kph – it should take you half an hour to reach it.

Timing

By walking for half an hour or so, you should be close to your objective.

This is not as easy as it sounds.

Things to consider are:

Going Uphill. Going Downhill.Fitness. Terrain. Load.

TimingUse your map and Naismith’s rule to calculate the time it will take to get from one place to another.

NAISMITH’S RULE

Carrying little –

5kph + 1min for every contour climbed.with a load –

4kph + 1½min for every contour climbed.

Plus½ min for every contour down a STEEP slope

TimingUse your map and Naismith’s rule to calculate the time it will take to get from one place to another.

Therefore,with a load:

4km per hour + 30 mins for every 200m uphill and10 mins for every 200m going down steep hills

PacingWhere very accurate distance measurement is required you could try counting the number of paces you take.

This practice is used

by orienteerers and with

lots of practice can be

very accurate indeed –

But over short distances only.

Errors

No matter which method of estimating distanceyou choose,

there will be an error attached to it.

This is particularly true when you are inexperienced.

If you add to this the possible error

in measuring direction, you will begin to see the difficulties that can lie ahead.

ErrorsAssuming a possible error of +/- 10%

in measuring distance travelled and one of +/- 4° when measuring direction,

you can see how quickly your area of uncertaintycan grow as you walk along.

The lessons you must learn from this are:

Keep the legs of your route as short as possible.

Practice your compass work until you can take accurate bearings.

Practice pacing and timing to reduce the error rate.

Errors

55

66

77

44

Check of UnderstandingUsing a compass to take a bearing on a distant object

what would you do first?

Turn the capsule housing to align the orienting lines with the object

Align the red compass needle with the object

Point the direction of travel arrowat the object

Turn the capsule housing to subtract the GMA

Check of UnderstandingWhat is the best way to measure distance on a map

without a pair of dividers?

Fold the paper to use the map scale

Use the edge of a compass

Make dividers with your fingers

Draw a pencil line and measure it

Check of UnderstandingMeasuring distances accurately whilst hillwalking

is important because it:

Chooses the shortest route

Calculates your speed of travel

Pinpoints your position accurately

Keeps you on schedule

Check of UnderstandingHow much time should be added for every

200 metres climbed with a pack, according to Naismith’s rule?

30 mins

15 mins

25 mins

20 mins

Check of UnderstandingWalking 1 km over reasonably flat ground in 20 mins.

How long will it take to cover 4.5km?

120 mins

40 mins

90 mins

60 mins

Check of UnderstandingWhen walking on a bearing, in good visibility,

the best technique is to . . .

Send a team member 50 metres ahead and walk to them

Follow your compass and ignore the countryside

Select an object 10 metres ahead and walk to it

Select a feature along your intended route of travel

Check of UnderstandingWhen navigating,

in order to reduce errors to a minimum, you should . . .

Never follow the established paths and tracks

Always follow the established paths and tracks

Measure distance and bearing as accurately as possible

Walk as quickly as possible to your destination

Leading Cadet Training

Basic Navigation

End of Presentation