Map Reading & Navigation Prepared by: The Expedition Company Limited

Map Reading & Navigation

Prepared by: The Expedition Company Limited

IntroductionIntroduction

This clear and simple tool is designed to provide you with the basic skills with which to learn to

map read.Using a step by step process, you can progress

comfortably at your own pace, with practical exercises and illustrations in every section to

help you learn.


EquipmentEquipment

Equipment requirements are simple. You will need a:

Ordnance Survey MapOrdnance Survey Map

Silva CompassSilva Compass

Sharp pencilSharp pencil

Plain PaperPlain Paper

Fine StringFine StringPrepared by: The Expedition Company Limited

Course ContentCourse Content

• Maps• A brief History• Components

– Type/Scale– Symbols– Plotting a location– Measuring distance– Relief

• The Compass– Components

• North– True– Grid– Magnetic

• Map & compass work

Route Planning & Route Planning & SafetySafety


Map .noun. Flat Map .noun. Flat representation of representation of the earth or some the earth or some part of it with its part of it with its

physical or physical or political features political features or of the heavensor of the heavens


DefinitionDefinition

HistoryHistoryEver since man has been able

to write and draw there is evidence to also show that he has recorded routes on land

and sea.Where maps were originally shown on clay tablets and

papyrus, we can now display them on paper and even CD

Rom!Prepared by: The Expedition Company Limited

The Ordnance Survey MapThe Ordnance Survey Map

Ordnance Surveymaps come in a

variety of different formats and this

guide will show you how to choose

which one is best suited for your own

use.


Types of MapTypes of MapThe importance of choosing the right map.The importance of choosing the right map.

Scale Map to Ground Activity1:1,000,000 1cm = 10km UK Map

1:250,000 1cm = 2,500m Use in car, motorbike

1:100,000 1cm = 1,000m Cycling, route planning

1:50,000 1cm = 500m General Purpose map

1:25,000 1cm = 250m Standard walking map1:15,000 1cm = 150m Orienteering


SymbolsSymbols

We interpret both man made and natural features on the map, through a system of symbols.

Every Ordnance Survey map has a key showing the definition of each symbol to help you. We will look at a few of the more

common symbols. Prepared by: The Expedition Company Limited

Symbol examplesSymbol examples


Symbol examplesSymbol examples


Grid linesGrid lines

• Every Ordnance Survey map is covered in a series of grids.

• By learning to use these grids we are able to locate a particular point on a map.


DistanceDistance

• Grid lines on all Ordnance Survey Maps are spaced 1km apart, regardless of regardless of scale.scale.

• This makes it easy to judge the rough distance between points by counting squares.

1 km1 km

1.5 km1.5 km


Grid LinesGrid Lines

52

51

50

4962 63 64 65 66

64 65 6663

50

51

52

Vertical Lines = Eastings

Horizontal Lines = Northings

Reading a Grid ReferenceReading a Grid Reference

• Grid references should be read in the following order:

– Eastings - Along the Corridor– Northings - Up the Stairs


52

51

50

4962 63 64 65 66

64 65 6663

50

51

52

Plotting a Grid SquarePlotting a Grid Square

Along the Along the CorridorCorridor

& Up & Up

ThThe e

StairsStairs

52

51

50

4962 63 64 65 66

6464 65 6663

5050

51

52

Plotting a Grid SquarePlotting a Grid Square

Grid: 64 5064 50

Accurate PlottingAccurate Plotting

• Having plotted the grid Square (1km x 1km) you will often need to establish the accurate location of a point or feature within the Square.

• This is achieved by dividing the square into a further ten Eastings (Vertical lines) & Northings (Horizontal lines).

• These additional lines are read in exactly the same manner as before.


Accurate PlottingAccurate Plotting (One Grid Square)

0

2

1

6

5

4

3

8

9

7

0

1 2 30 4 5 6 7 8 9 0

6464

5050

1 km1 km

1 km1 km

Plotting an accurate locationPlotting an accurate location100 metre accuracy100 metre accuracy

5050

52

51

49

6464 65 6663

Grid: 646 Grid: 646 504504

62

Measuring DistanceMeasuring Distance

By using the scale at the bottom of each Ordnance Survey Map you can

easily convert a measurement in centimetres into a real distance on

the ground.


Measuring DistanceMeasuring Distanceusing a Silva Compassusing a Silva Compass

Nearly all compasses have a centimetre scale which proves an effective tool for measuring the distance between two points.


Measuring DistanceMeasuring Distanceusing a Piece of Stringusing a Piece of String

• Trace your route on the map with a piece of string and mark the points at which the route starts and finishes on the string.

• Place the string against the scale on the map and read off the equivalent distance on the ground.


Measuring DistanceMeasuring Distanceusing a Map Measurerusing a Map Measurer

• Map measurers are purposefully designed for measuring distances on a map.

• Trace your route with the small wheel at the bottom of the measurer and it will automatically tell you the distance on the ground via a rotating scale.


ReliefRelief

• Relief refers to the way in which height is displayed on a map.

• This is shown by a system of lines called ‘Contours’.


Contour LinesContour Lines• Contour lines link

points of equal height on the map at ten metre intervals.

• Contours display how many metres land is above sea level.



DefinitionDefinitionCompass .nounCompass .noun

. Instrument . Instrument showing user showing user

the direction of the direction of north and other north and other points of the ~ points of the ~

by means of by means of magnetic magnetic

needleneedle

The CompassThe Compass There are a

variety of different

compass styles available to you. We suggest that

to begin with, you use a Silva compass similar

to the one pictured here.


The CompassThe Compass• They were originally discovered by the Chinese

5000 years ago.• They are made in a variety of forms for use on

land, above and below the sea and in the air.• Examples of activities in which they are used are:

– Hillwalking - Mountaineering– Cycling - Surveying– Driving - Military– Sailing - Scuba Diving – Flying - Orienteering


Cardinal Points (Compass Points)

NortNorthh

WestWest EastEast

SoutSouthh

North East : 45ºNorth East : 45º

South West : South West : 225º225º

South East : South East : 135º135º

North West : North West : 315º315º

270º270º

180º180º

90º90º

0º & 360º0º & 360º


Bearings are taken in degreesº- The cardinal points are divided up into 360º & measured

clockwise.NortNorthh

WestWest EastEast

SoutSouthh

North East : 45ºNorth East : 45º

South West : 225ºSouth West : 225º South East : South East : 135º135º

North West : North West : 315º315º

0º & 360º0º & 360º

270º270º

180º180º

90º90º


Parts of the CompassParts of the Compass

• The compass can be broken down into various components.

• We will look at each component separately to define its use.


Base Plate & Compass Base Plate & Compass HousingHousing

• The Base Plate is the mounting for the housing and displays a variety of information eg. Scale ruler.

• The Compass Housing contains a magnetic bar, called the Needle Needle and defines the points of the compass on a rotating bezel.


CompassCompass HousingHousing

Base PlateBase Plate

The Compass NeedleThe Compass Needle

• The needle is suspended in liquid which enables it to move freely, always settling with the red end pointing NorthNorth.

• Some needles are Luminous to help navigation in the dark.


NeedlNeedlee

Direction of Travel ArrowDirection of Travel Arrow

• The Direction of Direction of Travel ArrowTravel Arrow indicates the direction along which you wish to travel or take a bearing.

• The arrow is fixed within the base plate.

• The sides of the base plate run parallel to the arrow.


Direction of Travel Direction of Travel ArrowArrow

The Index LineThe Index Line

• The Index Line is a fixed line within the Compass Housing and is in line with the direction of travel arrow.

• The Index Line marks the bearing you set by rotating the bezel.


Index Index LineLine

Orienting LinesOrienting Lines• These are displayed

within the rotating Compass Housing and are designed to be aligned parallel with the EastingsEastings on a map.

• The orienting lines on some compass models show one half of the lines in red to depict north.


Orienting Orienting LinesLines

Compass ScaleCompass Scale

• Nearly all compasses have a centimetre scale along the edge of the base plate to enable you to measure distances.

• Used in conjunction with the scale at the bottom of the map, the compass scale enables you to calculate the distance on the ground.


Compass Compass ScaleScale

Points to NotePoints to Note• Stand clear of metal objects when using the

compass. They will cause the needle to deviate and create inaccurate bearings. Objects as small as watches can make a difference.

• Hold the compass as flat as possible to allow the needle to move freely.

• Look after your compass - try to avoid dropping or knocking it.

• Store away from other compasses and electrical equipment.

• Your compass may need replacing if a large air bubble forms in the Compass Housing.


True / Grid / Magnetic NorthTrue / Grid / Magnetic North

• True NorthTrue North and South are at the geographical poles.

• Grid NorthGrid North is the direction to which all Ordnance Survey Maps are oriented. We take our map bearings using Grid North.

• Magnetic NorthMagnetic North is the direction a compass points to and in the UK it is located approximately 5º West of Grid North.

Magnetic VariationMagnetic Variation

• The difference in degrees between Magnetic (Mag)Magnetic (Mag) NorthNorth and Grid Grid NorthNorth is referred to as the Magnetic Variation (usually 5º West in UK.)

True NorthTrue North

Grid NorthGrid North

Magnetic Magnetic NorthNorth

5º5º

Magnetic VariationMagnetic Variation

• It is important to understand the relationship between GridGrid & MagMag north as this will become important when we start to convert bearings to and from a map.

True NorthTrue North

Grid NorthGrid North

Magnetic Magnetic NorthNorth

5º5º

Map & Compass WorkMap & Compass Work

• Having looked separately at both the Ordnance Survey Map & Silva Compass the following example will demonstrate how they are used together.

• If you are unsure about anything which has been covered in the previous slides, look back now before you progress to the next section.

Map & Compass WorkMap & Compass Work• When working from the map we deal with

Grid Bearings.• When following a compass on the ground

we work with Magnetic Bearings.• There is a simple system which enables us

to convert Grid to Mag and Mag to Grid.• The system refers to whether we add or

subtract the magnetic variation to convert the bearing.

Map & Compass WorkMap & Compass Work

Mag to Grid…………. GET RID

Grid to Mag………….ADD

(usually 5º West in UK)

Map to GroundMap to Ground

Grid to Mag………….ADD


• Select a start and finish point on the map.

• Line up the edge of the compass with the line along which you intend to travel.

• Keeping the base plate static - rotate the compass housing until the orienting lines are parallel with the Eastings and the red ‘N’ is pointing to North on your map.


• Read the bearing shown on the housing from the index line.

• Remember - Grid to Mag……Add.• Add the magnetic variation shown at

the top of the map (usually 5º West in UK.)

• You now have your magnetic bearing of the course you have chosen. The next step is to orientate yourself.

OrientatingOrientating• Hold your compass level and steady.

• Turn your body until the red end of the needle is in line with the Red ‘N’ on the Housing.

• The direction of travel arrow is now pointing along the route you chose from the map and you are ready to travel.

Following the Compass Following the Compass BearingBearing

• Hold your compass level and steady.• Ensure that the red end of the needle is in line

with the Red ‘N’ on the Housing every time you refer to the compass bearing.

• Follow the direction of travel arrow. You will find it easier to line up the direction arrow with a physical feature on the ground (eg tree, pylon, tower). Use this as a reference point which you can move towards. This is easier than following the compass every inch of the way.

Ground to MapGround to Map

Mag to Grid…………. GET RID


• 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.• Rotate the housing until the red end of

the needle is in line with the Red ‘N’ on the Housing.


• This is your Mag bearing which you can either travel along or convert to a grid bearing.

• To plot on the map you should first locate your own position and mark it.

• Convert the Mag bearing to a Grid bearing by Mag to Grid……Get Rid. (Usually 5º West in UK.)

• Subtract the magnetic variation.


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 on the map. The edge of the compass should run through your

position and show the bearing on the map.


By turning your body until the red end of the needle is in line with the Red ‘N’ on the Housing you have

now oriented yourself and the map.

Quick OrientationQuick OrientationYou can orientate yourself and the map to the

ground at any time using this easy system:

A. Lay the compass on the map.B. Line the edge of the compass

and the orienting lines up with the Eastings.

C. Turn your body until the red end of the needle is in line with the Red ‘N’ on the Housing.

You and your map are now facing North.

Route PlanningRoute Planning

• It is important, where possible, to take time in planning your route before you start.

• This will help you to identify any problems early and to estimate how far you intend to travel and how long it should take.


Route CardRoute Card• A route card is simple to produce and

makes navigation on the ground simple. A basic format is shown here:

Date: 21/07/99 Number of Persons: 2Time Grid Bearing Distance Remarks0900 501 412 90º 2km Car Park to Bridge0925 521 412 180º 5km Bridge to hilltop1030 521362 240º 1km Hilltop to wood1045 514358 300º 1.5km Wood to church


Route Planning & SafetyRoute Planning & Safety

• Make sure that your route is well within your ability and that you are in possession of the right equipment.

• Leave a copy of your route card with a friend or contact in order that you can be easily found in an emergency.


Map Reading & Navigation


Ordnance SurveyRomsey Road

SOUTHAMPTON

United Kingdom, SO16 4GU

www.ordsvy.gov.uk

The Expedition Company LimitedPo Box 17

WiveliscombeTaunton, TA4 2YL

Tel: +44 (0) 1984 624780 Fax: +44 ()) 1984 629045email: [email protected] Web: www.expedition.co.uk

Produced in association with

Documents

Map Reading & Navigation Prepared by: The Expedition Company Limited