What is Navigation? Good Navigation is knowing: Where you are on the map Where you want to go How to choose the best route to follow What is.

What is Navigation?What is Navigation?

Good Navigation is knowing:Good Navigation is knowing: Where you are on the mapWhere you are on the map Where you want to goWhere you want to go How to choose the best route to How to choose the best route to

followfollow What is needed?What is needed? Good map reading skills Good map reading skills Good compass workGood compass work

True North or Grid North?True North or Grid North?

An OS map has An OS map has grid linesgrid lines which enable you to which enable you to identify a small area by its identify a small area by its grid referencegrid reference..

Grid linesGrid lines cover a cover a flat flat surfacesurface (the map) and so (the map) and so are regular. However, are regular. However, lines of longitude and lines of longitude and latitudelatitude cover the cover the curved curved surfacesurface of the earth with of the earth with the lines of longitude the lines of longitude getting closer and closer getting closer and closer together as they reach the together as they reach the North and South poles.North and South poles.

What does this mean? Grid lines do What does this mean? Grid lines do not actually point to not actually point to True NorthTrue North- - instead they point to an imaginary instead they point to an imaginary point called point called Grid NorthGrid North. (The . (The difference is insignificant and is no difference is insignificant and is no more than 2more than 2))

In navigation you must always use In navigation you must always use Grid North as your referenceGrid North as your reference

Setting or orientating your mapSetting or orientating your map Orientation of your Orientation of your

mapmap by eye by eye Turn your map in such Turn your map in such

a way that identifiable a way that identifiable features on the ground features on the ground are in their correct are in their correct position relative to the position relative to the map.map.

EASY TO PIN POINT EASY TO PIN POINT POSITON AT ANY TIMEPOSITON AT ANY TIME

(It should become (It should become easier for you to see easier for you to see changes in direction, changes in direction, junctions and the junctions and the appearance of features appearance of features which will confirm your which will confirm your actual position.)actual position.)

Finding North without a compassFinding North without a compass3 methods for finding north without a 3 methods for finding north without a

compasscompass

1. The Pole Star1. The Pole Star In the northern In the northern

Hemisphere the Hemisphere the direction of the north direction of the north pole is indicated by pole is indicated by the position of the the position of the Pole Star. First find Pole Star. First find the Great Bear or the Great Bear or Plough and then follow Plough and then follow the pointers to the the pointers to the Pole StarPole Star

2. Using a Watch2. Using a Watch Looking at the sun, Looking at the sun,

hold your watch hold your watch horizontally with the horizontally with the hour hand pointing at hour hand pointing at the sun. Now bisect the sun. Now bisect (halve) the angle (halve) the angle between the hour hand between the hour hand and the 12 o’clock and the 12 o’clock position. This line position. This line points due south. In points due south. In British summer time British summer time (Apr-Oct) bisect the (Apr-Oct) bisect the angle between the angle between the hour and the 1 o’clock hour and the 1 o’clock position.position.

3. The Shadow Method3. The Shadow Method This method can only This method can only

be used if the sun is be used if the sun is shining significantly to shining significantly to cast shadows.cast shadows.

Place a stick upright Place a stick upright in the ground and in the ground and mark the end of its mark the end of its shadow using a small shadow using a small stone. Wait for 10-15 stone. Wait for 10-15 minutes and use a minutes and use a second stone to mark second stone to mark the new position of the new position of the stick’s shadow. A the stick’s shadow. A straight line between straight line between the two markers runs the two markers runs roughly west to east.roughly west to east.

Magnetic NorthMagnetic North

The Earth’s The Earth’s magnetic north magnetic north pole does not pole does not coincide with its coincide with its geographical north geographical north pole (true north). In pole (true north). In the British Isles the the British Isles the magnetic north magnetic north pole is presently pole is presently about 5about 5west of west of true north.true north.

The The magnetic magnetic variationvariation as it is as it is called is different in called is different in different parts of the different parts of the world and must be world and must be allowed for when allowed for when using a map and using a map and compass for compass for navigating. To help navigating. To help you, the magnetic you, the magnetic variation is always variation is always displayed on the displayed on the bottom of an OS map.bottom of an OS map.

To further complicate To further complicate things the things the magnetic magnetic north is not fixednorth is not fixed and moves very slowly and moves very slowly and changes position and changes position a little each year. This a little each year. This movement can be movement can be predicted and predicted and adjustments made to adjustments made to compensate.compensate.

The The GRID MAGNETIC ANGLEGRID MAGNETIC ANGLE (GMA) is the angular difference (GMA) is the angular difference between the grid north and the between the grid north and the magnetic north and is displayed on magnetic north and is displayed on every OS map in the centre of the every OS map in the centre of the top margin.top margin.

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The CompassThe CompassThe Silva CompassThe Silva Compass

Main partsMain parts Free moving magnetic Free moving magnetic

needle – half red (points needle – half red (points North) half white (points North) half white (points South)South)

Direction of travel arrow on Direction of travel arrow on compass platecompass plate

360360 marked around the marked around the rimrim

Orientating lines marked Orientating lines marked on its baseon its base

A rotating capsule filled A rotating capsule filled with a fluid to ‘damp’ the with a fluid to ‘damp’ the compass needle compass needle

Careful not to drop and store it away Careful not to drop and store it away from electrical appliances that contain from electrical appliances that contain strong magnets (e.g. TV, telephones strong magnets (e.g. TV, telephones etc..)etc..)

Magnetic DeviationYour compass needle is a small magnet and will be affected by ferrous metals placed close by.

Your magnet will deviate from its true position- so take care when

using your compass.Try the following:

Setting the map with a compassSetting the map with a compass

Turn the compass capsule Turn the compass capsule until the grid magnetic until the grid magnetic angle (GMA) is set against angle (GMA) is set against the direction arrow (say 6the direction arrow (say 6))

Place the compass onto Place the compass onto the map so that the long the map so that the long edge of the compass edge of the compass matches the N-S grid lines matches the N-S grid lines and the direction of travel and the direction of travel arrow points to the top of arrow points to the top of the map.the map.

Turn the map and compass Turn the map and compass TOGETHERTOGETHER until the until the compass needle falls inside compass needle falls inside the orientating arrow – red the orientating arrow – red end pointing Northend pointing North

Setting a compass headingSetting a compass heading

Compass BearingsCompass Bearings If you are unable to identify features If you are unable to identify features

to set your map you can use your to set your map you can use your compass.compass.

(E.g. You are at GR 042 166 on the (E.g. You are at GR 042 166 on the map and you are planning to walk to map and you are planning to walk to the church at GR 067 192)the church at GR 067 192)


1.Place the compass on 1.Place the compass on the map with its long edge the map with its long edge running through both running through both points and the direction of points and the direction of travel arrow pointing in travel arrow pointing in the direction you wish to the direction you wish to travel. (You do not need to travel. (You do not need to set the map for this set the map for this operation)operation)

2. Hold the compass plate 2. Hold the compass plate firmly in this position and firmly in this position and turn the compass capsule turn the compass capsule until the orienting lines on until the orienting lines on its base are parallel to the its base are parallel to the north-south grid lines and north-south grid lines and the orienting arrow points the orienting arrow points to the top of the map.to the top of the map.


3. The compass now 3. The compass now registers the number of registers the number of degrees between grid degrees between grid north and your intended north and your intended direction of travel. Now direction of travel. Now you must add the GMA you must add the GMA (say 6(say 6)- so turn the )- so turn the capsule to add another capsule to add another 66..

4. Remove the compass 4. Remove the compass from the map and hold it in from the map and hold it in front of you so that it is front of you so that it is level and the direction of level and the direction of travel arrow points away travel arrow points away from you. Rotate your from you. Rotate your body until the magnetic body until the magnetic needle falls within the needle falls within the orienting arrow on the orienting arrow on the base of the capsule- red base of the capsule- red end pointing north.end pointing north.


5. The direction of travel arrow should now 5. The direction of travel arrow should now point in the direction you need to walk.point in the direction you need to walk.

REMEMBER GRID to MAG - REMEMBER GRID to MAG - ADDADD

Walking on a bearingWalking on a bearing

Always Always choose a choose a feature in the far feature in the far distancedistance- possibly on - possibly on the horizon, and walk the horizon, and walk to that – to that – Avoid Avoid walking while walking while staring at your staring at your compass!compass!

If it is If it is poor visibilitypoor visibility- - sight on an object at sight on an object at the limit of you the limit of you visibility, a rock, a visibility, a rock, a bunch of reeds. As bunch of reeds. As you approach your you approach your chosen object, others chosen object, others will appear behind it will appear behind it and in line with it. Use and in line with it. Use these continually these continually appearing objects to appearing objects to do your straight line do your straight line compass march.compass march.

Transferring from compass to Transferring from compass to mapmap

You can take a compass bearing and You can take a compass bearing and convert it to a map bearing in order convert it to a map bearing in order to identify a feature or to help to identify a feature or to help pinpoint your position.pinpoint your position.

(E.g. You are on the path at GR 051 (E.g. You are on the path at GR 051 179 and you see a church in the 179 and you see a church in the distance that you want to identify on distance that you want to identify on the map)the map)


1. Point the direction 1. Point the direction of travel arrow at the of travel arrow at the distant church.distant church.

2. Hold the compass 2. Hold the compass in this position and in this position and turn the capsule until turn the capsule until the orienting arrow the orienting arrow lies directly beneath lies directly beneath the north end of the the north end of the compass needle. compass needle. This gives the This gives the magnetic bearing.magnetic bearing.

3. Now turn the 3. Now turn the capsule to deduct the capsule to deduct the GMA (6GMA (6). This now ). This now gives the grid bearing.gives the grid bearing.

4. Place the compass on the map (you 4. Place the compass on the map (you do not have to set the map) with its do not have to set the map) with its long edge passing through your long edge passing through your present position, on the path at GR 051 present position, on the path at GR 051 179. 179. DO NOT TURN the capsuleDO NOT TURN the capsule..

5. Pivot the whole compass around 5. Pivot the whole compass around your position until the orienting lines your position until the orienting lines are parallel to the north-south grid are parallel to the north-south grid lines and the orienting arrow points to lines and the orienting arrow points to north on the mapnorth on the map


The edge of the compass that runs The edge of the compass that runs through your position should now through your position should now run through, or point at, the symbol run through, or point at, the symbol for a church you can see in the for a church you can see in the distance.distance.

REMEMBER MAG to GRID – get RIDREMEMBER MAG to GRID – get RID

Resection – Finding where you Resection – Finding where you areare

If you have a vague idea where you If you have a vague idea where you are on a map and wish to determine are on a map and wish to determine your position more accuratelyyour position more accurately

You must be able to identify at least You must be able to identify at least 3 features on the ground around you 3 features on the ground around you (i.e. the edge of a wood, a church (i.e. the edge of a wood, a church and a hill)and a hill)

Resection – Finding where you Resection – Finding where you areare

Take each feature in Take each feature in turn, take its compass turn, take its compass bearing, convert it to a bearing, convert it to a grid bearing and plot its grid bearing and plot its position on the map. position on the map.

Draw a faint pencil line Draw a faint pencil line along the long edge of along the long edge of your compass so that it your compass so that it passes through the passes through the known feature.known feature.

Repeat this for the two Repeat this for the two other features and the other features and the point where all 3 lines point where all 3 lines cross marks your cross marks your position. (The lines rarely position. (The lines rarely meet at a point; take meet at a point; take position as being near position as being near the centre of the triangle the centre of the triangle formed.)formed.)

Scales and RoamersScales and Roamers

Using a RoamerUsing a Roamer- - A Roamer is used A Roamer is used to find a 6 figure to find a 6 figure grid reference grid reference more accurately more accurately than by estimation. than by estimation.

You must have the You must have the correct roamer correct roamer scale for the mapscale for the map

Place the corner of the correct roamer on the Place the corner of the correct roamer on the map feature whose reference you want, then map feature whose reference you want, then read from where the scales intersect the grid read from where the scales intersect the grid lines.lines.

Always read the nearest low figure (SW corner)Always read the nearest low figure (SW corner)

Measuring distances on a mapMeasuring distances on a map Use dividersUse dividers-Measure -Measure

distance between two distance between two features on the map by features on the map by opening the dividers to opening the dividers to touch each feature and touch each feature and then transfer this then transfer this measurement onto the measurement onto the scale at the bottom of the scale at the bottom of the map. map. DO NOT PUNTURE DO NOT PUNTURE THE MAP!THE MAP!

Straight Edge of PaperStraight Edge of Paper- - Place the piece of paper Place the piece of paper between the features on between the features on the map and mark their the map and mark their position on the paper. Now position on the paper. Now line this up with the scale line this up with the scale at the bottom of the map. at the bottom of the map. By placing your paper on By placing your paper on the scale so that the right the scale so that the right hand mark is on a whole hand mark is on a whole number of units, the number of units, the second mark should fall on second mark should fall on the tenths to the left of the the tenths to the left of the zero.zero.

AnswersAnswers

Using this map answer the Using this map answer the followingfollowing

Using this map answer the Using this map answer the followingfollowing

Practical NavigationPractical Navigation

Measuring distance on the Measuring distance on the groundground

There are two ways to estimate There are two ways to estimate distance:distance:

Timing b) PacingTiming b) Pacing

a)Timinga)Timing – How long – How long does it take you to does it take you to walk 1 km?walk 1 km?

If you know how fast If you know how fast you walk, then you you walk, then you should be able to work should be able to work out how long it will out how long it will take you to cover a take you to cover a known distance.known distance.

Speed =distance / time Speed =distance / time Therefore Therefore

time = distance / speedtime = distance / speed E.g. If you need to walk E.g. If you need to walk

2 km and you can walk at 2 km and you can walk at 4 km/h. How long will it 4 km/h. How long will it take you?take you?

Time = 2 km / 4 km/h = Time = 2 km / 4 km/h = 0.5 h or ½ hour0.5 h or ½ hour

Things to considerThings to consider

Going UphillGoing Uphill – – Naismuth’s ruleNaismuth’s rule

Add ½ hour for Add ½ hour for every 200 m of every 200 m of climbingclimbing

Going downhillGoing downhill – – extra timing for extra timing for climbing usually climbing usually cancels with faster cancels with faster walking on descents. walking on descents. However, very steep However, very steep descents may require descents may require more care. In this more care. In this case:case:

Add 10 minutes for Add 10 minutes for every 200m in every 200m in steep descentsteep descent

Things to considerThings to consider FitnessFitness – A group can – A group can

only move at the speed only move at the speed of the slowest member. of the slowest member.

TerrainTerrain – It is not always – It is not always possible to tell from a possible to tell from a map just how rough the map just how rough the terrain will be. Marshes, terrain will be. Marshes, boulder fields and forest boulder fields and forest can all slow walkers can all slow walkers down.down.

Unsure of Terrain – Unsure of Terrain – Allow for slow Allow for slow progressprogress

LoadLoad – Carrying a heavy – Carrying a heavy pack can slow a walker by pack can slow a walker by as much as 50% of normal as much as 50% of normal speed. speed.

Heavy Load – Reduce Heavy Load – Reduce overall speed to 3 km/h overall speed to 3 km/h or even 2 km/hor even 2 km/h

PacingPacing

Counting pacesCounting paces – This involves – This involves counting paces over short distances counting paces over short distances only. only.

-Count number of double paces (each -Count number of double paces (each time the same foot hits the ground)time the same foot hits the ground)

-Different terrain will require -Different terrain will require adjustmentsadjustments

ErrorsErrorsTry to be as accurate as possible – Try to be as accurate as possible – errorserrors in both in both

distance and direction could result in distance and direction could result in huge huge uncertaintiesuncertainties after only short distances. after only short distances.

Error of ± 10% for distanceError of ± 10% for distance Error of ± 4Error of ± 4 for direction for direction RESULT – Huge AREA of uncertaintyRESULT – Huge AREA of uncertainty

After 1 km uncertainty After 1 km uncertainty 4 4 football pitchesfootball pitches

After 3 km uncertainty After 3 km uncertainty 36 36 football pitches!!!football pitches!!!

Keep the legs of your route as Keep the legs of your route as short a possibleshort a possible

Practice compass workPractice compass work Practice Pacing and timing Practice Pacing and timing

distancesdistances

Good Navigational TechniquesGood Navigational Techniques

1. Handrailing1. Handrailing- - This This technique uses easy technique uses easy to follow linear to follow linear features to direct you features to direct you to your final to your final destination. The linear destination. The linear feature is used as a feature is used as a ‘handrail’.‘handrail’.

Use ‘handrailing’ to Use ‘handrailing’ to get you from get you from position A to the position A to the camp site.camp site.


2. Aiming off2. Aiming off-- Imagine Imagine you are at point A and you you are at point A and you want to cross the river at want to cross the river at the bridge. the bridge.

Aiming directly for the Aiming directly for the bridge – chances are that bridge – chances are that you would miss it, and you you would miss it, and you would not know to turn would not know to turn upstream or downstream upstream or downstream to look for the bridge.to look for the bridge.

Aiming off slightly to one Aiming off slightly to one side- you would then know side- you would then know which way to turn when which way to turn when you hit the stream.you hit the stream.


3. Contouring3. Contouring Is it better to go round a Is it better to go round a

hill or up over the top?hill or up over the top? The two routes may take The two routes may take

the same time, but the same time, but contouring round takes contouring round takes less effort.less effort.

To consider-To consider- Contouring requires very Contouring requires very

careful navigation, careful navigation, particularly in poor particularly in poor visibility (tendency to lose visibility (tendency to lose height and to travel too far height and to travel too far around the curve)around the curve)


Try this: Try this: The route around the spur is 4 km The route around the spur is 4 km

and will take you about 1 hour to and will take you about 1 hour to walk.walk.

The route over the hill is only 2 km The route over the hill is only 2 km long but you have to climb 200mlong but you have to climb 200m

Use Naisth’s rule, how long would Use Naisth’s rule, how long would this route take to walk?this route take to walk?


4. Attack points4. Attack points Aim for an easily Aim for an easily

identifiable feature identifiable feature close to your target. It close to your target. It pays to go slightly out pays to go slightly out of your way to hit a of your way to hit a definite target, in definite target, in order to increase your order to increase your chances of reaching chances of reaching your final objective your final objective successfully.successfully.

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About weather-About weather-

On expedition you are very much On expedition you are very much at the at the mercy of the weathermercy of the weather (elements) (elements)

You must learn how to exploit the weather You must learn how to exploit the weather and work with it rather than against it.and work with it rather than against it.

(e,g, choosing route with wind at your (e,g, choosing route with wind at your back, altering route to take in summits not back, altering route to take in summits not shrouded in cloud or setting up cam before shrouded in cloud or setting up cam before the heavens open)the heavens open)

Knowledge of weather is requiredKnowledge of weather is required

Listening to the daily and local Listening to the daily and local forecast is vital – start a week before forecast is vital – start a week before you go and also get the very latest you go and also get the very latest version for your specific area.version for your specific area.

Unfortunately weather has a Unfortunately weather has a habit of changing rapidlyhabit of changing rapidly

You must be able to predict the You must be able to predict the weather as you goweather as you go

Main Air MassesMain Air Masses

Polar MaritimePolar Maritime – picks – picks up water vapourup water vapour

Summer – cool winds, Summer – cool winds, heavy thunder heavy thunder showers, thunder showers, thunder storms in mountainsstorms in mountains

Winter – Heavy Winter – Heavy showers in west with showers in west with snow in mountains. snow in mountains. Clear skies at night in Clear skies at night in the east giving frostthe east giving frost

Returning Polar Returning Polar MaritimeMaritime- wetter that - wetter that polar maritime airpolar maritime air

Summer- Warm with Summer- Warm with squally showers and squally showers and storm inlandstorm inland

Winter – Stratus cloud. Winter – Stratus cloud. Showers in the Showers in the western mountainswestern mountains

Tropical MaritimeTropical Maritime – –brings warm wet airbrings warm wet air

Summer – Warm Summer – Warm south-west winds. Low south-west winds. Low stratus cloud over stratus cloud over west coast.west coast.

Winter - Stratus cloud, Winter - Stratus cloud, hill fog and drizzle, hill fog and drizzle, clearing in the north-clearing in the north-west. Warm with west. Warm with prolonged rainfall in prolonged rainfall in westerly mountainswesterly mountains

Tropical ContinentalTropical Continental- - warm air - not able to warm air - not able to pick up moisturepick up moisture

Summer only – Very Summer only – Very hot and dry, hazy with hot and dry, hazy with occasional thunder occasional thunder stormsstorms

Arctic MaritimeArctic Maritime- very cold- - very cold- not able to pick up not able to pick up moisture as it travels southmoisture as it travels south

Summer – Very cold with Summer – Very cold with frequent heavy showers.frequent heavy showers.

Winter – Very cold strong Winter – Very cold strong north, north-easterly north, north-easterly winds. Heavy snow winds. Heavy snow showers in north.showers in north.

Polar ContinentalPolar Continental- very - very cold in winter, warm in cold in winter, warm in summer – Southern summer – Southern England not able to pick up England not able to pick up moisture, Scotland – moisture, Scotland – crosses more water crosses more water therefore picks up more therefore picks up more moisture.moisture.

Summer- Warm and dry, Summer- Warm and dry, cloud free. East coast cloud free. East coast tends to be cool and tends to be cool and showery with coastal fog in showery with coastal fog in the norththe north

Winter – Sleet and snow Winter – Sleet and snow showers in the north. Cold showers in the north. Cold strong east windsstrong east winds

Fronts and Frontal DepressionsFronts and Frontal Depressions

Isobars – lines which join areas of equal Isobars – lines which join areas of equal pressurepressure

Close IsobarsClose Isobars – Strong Winds – Strong Winds Spread out IsobarsSpread out Isobars – Light Winds or breezes – Light Winds or breezes

Areas of Low PressureAreas of Low Pressure – Called – Called Depressions or Lows – The winds Depressions or Lows – The winds circulate in an anticlockwise circulate in an anticlockwise direction- generally poor weatherdirection- generally poor weather

Areas of High PressureAreas of High Pressure – Called – Called Anticyclones or Highs – The wind Anticyclones or Highs – The wind circulates in a clockwise direction- circulates in a clockwise direction- generally warm dry air bring periods generally warm dry air bring periods of fine clear weather.of fine clear weather.

Warm and Cold FrontsWarm and Cold Fronts- When two air masses - When two air masses meet, instead of mixing together, the less dense meet, instead of mixing together, the less dense warm air tends to rise over the cold more dense warm air tends to rise over the cold more dense air causing a drop in pressure. The cold air rushes air causing a drop in pressure. The cold air rushes in to fill the gap, producing a circular motion in to fill the gap, producing a circular motion toward the centre of the depression. In northern toward the centre of the depression. In northern Hemisphere- It goes in a anticlockwise direction.Hemisphere- It goes in a anticlockwise direction.

RULE – stand with your back to the wind, the RULE – stand with your back to the wind, the low (and worst of the weather) is on your low (and worst of the weather) is on your left.left.

Occluded FrontOccluded Front – When a Cold front – When a Cold front catches up with a Warm front. This catches up with a Warm front. This forms a continuous layer of cold air forms a continuous layer of cold air at ground level with the warm air on at ground level with the warm air on top.top.

Position A with your back Position A with your back to the lower wind and the to the lower wind and the upper wind is moving left upper wind is moving left to right – the depression to right – the depression has not yet reached you has not yet reached you and the weather is likely to and the weather is likely to deteriorate.deteriorate.

Position B with your back Position B with your back to the lower wind and the to the lower wind and the upper wind is moving from upper wind is moving from right to left, then the right to left, then the depression has passes and depression has passes and the weather is likely to the weather is likely to improve.improve.

Position C and Position D Position C and Position D with your back to the lower with your back to the lower wind is either moving wind is either moving toward you (at D) or toward you (at D) or moving away (at C), then moving away (at C), then there is likely to be little there is likely to be little immediate change in the immediate change in the weather. weather.

CloudsClouds

3 main types of clouds3 main types of clouds a) Cirrus- found only at high levels a) Cirrus- found only at high levels

and are composed of ice crystalsand are composed of ice crystals b) Cumulus- a lumpy or heaped cloudb) Cumulus- a lumpy or heaped cloud c) Status – featureless layer of cloudc) Status – featureless layer of cloud

QuestionsQuestions

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What is Navigation? Good Navigation is knowing: Where you are on the map Where you want to go How to choose the best route to follow What is.

Documents

grid north

earths magnetic north

reference slide

west of true north

pole star slide

good map

grid lines

os map