orienteering

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CUON SCOUT GROUP GREENVIEW SECONDARY SCHOOL 15 PASIR RIS STREET 21 SINGAPORE 518969 WEBSITE: http://cuonet.cjb.net

Table of Contents 1.0 Map Reading................................................................................................................. 3

1.1 Identify Map colors................................................................................................... 3

1.2 Identify Map Symbols............................................................................................... 4

1.3 Identify Marginal Information .................................................................................. 8

1.4 Identify Terrain Features........................................................................................... 9

1.4.1 Major.................................................................................................................. 9

1.4.2 Minor.................................................................................................................. 9

1.4.3 Supplementary ................................................................................................... 9

1.5 Identify Contours .................................................................................................... 20

1.6 Reading a Map ........................................................................................................ 25

1.6.1 Six Digit Map Grid Reference (MGR) ............................................................ 27

1.6.2 Eight Digit Map Grid Reference (MGR) ......................................................... 29

1.7 Using a map to determine your own position ......................................................... 30

1.7.1 Visual orientation of a map.............................................................................. 30

2.0 Using a Compass......................................................................................................... 32

2.1 Parts of a compass................................................................................................... 32

2.2 North: True, Grid, and Magnetic ............................................................................ 33

2.2.1 True North........................................................................................................ 33

2.2.2 Grid north......................................................................................................... 33

2.2.3 Magnetic north ................................................................................................. 34

2.3 Set a Map using Compass ....................................................................................... 36

2.4 Back Bearing........................................................................................................... 37

2.5 Determining your position on a map using a compass ........................................... 41

2.5.1 Resection.......................................................................................................... 41

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2.5.2 Intersection....................................................................................................... 47

2.6 Exploration with bearings ....................................................................................... 48

2.6.1 Line of Sight .................................................................................................... 48

2.6.2 Aiming Off....................................................................................................... 48

2.6.3 Baselines .......................................................................................................... 49

2.6.4 Walking around obstacles ................................................................................ 50

3.0 Glossary ...................................................................................................................... 51

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1.0 Map Reading

1.1 Identify Map colors

Black - Indicates cultural (man-made) features such as buildings and roads,

surveyed spot elevations, and all labels

Red-Brown - Combined to identify cultural features, all relief features, non-

surveyed spot elevations, and elevation, such as contour lines on red-light

readable maps

Blue - Identifies water features such as lakes, swamps, rivers, and drainage.

Green - Identifies vegetation such as woods, orchards, and vineyards

Brown - Identifies all relief features and elevation, such as contours on older

edition maps, and cultivated land on red-light readable maps

Red - Classifies cultural features, such as populated areas, main roads, and

boundaries, on older maps

Other - Occasionally other colors may be used to show special information.

These are indicated in the marginal information as a rule

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1.2 Identify Map Symbols

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1.3 Identify Marginal Information

• Geographic area and scale - top left

• Name of map sheet - top center

• Map edition, map series, and map sheet number - top right

• Legend - bottom left

• Bar scale, contour interval, grid reference box, and declination diagram -

bottom center

• Elevation guide, adjoining map sheet diagram, and boundaries box - bottom

right

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1.4 Identify Terrain Features

1.4.1 Major

• Hill

• Ridge

• Valley

• Saddle

• Depression

1.4.2 Minor

• Draw

• Spur

1.4.3 Supplementary

• Cliff

• Cut

• Fill

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1.5 Identify Contours

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Difference between gradual slope and cliff, notice the spacing between the

contour lines.

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1.6 Reading a Map

On the Singapore topographical map is a series of superimposed blue lines

forming squares measuring 1000 metres on each side. The vertical lines are

numbered from left to the right and the horizontal lines are numbered from

bottom to top.

The vertical lines are called EASTINGS because they run to the east, and the

horizontal lines are called NORTHINGS, because they run to the North.

Note: In every map reference, the EASTING is given first.

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1.6.1 Six Digit Map Grid Reference (MGR)

1. The first three digits is the easting and the last three digits is the

northing.

Note: A four digit MGR typically refers to a particular square.

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1.6.2 Eight Digit Map Grid Reference (MGR)

1. The first four digits is the easting and the last four digits is the

northing.

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1.7 Using a map to determine your own position

Before you can determine your own position on the ground using a map, you need

to orient (or set) the map. This simply means that you need to hold the map in

such a way that the true north arrow of the map points to true north (or north on

the map points to north in the actual countryside). The features depicted on the

map and the same features on the ground will then lie in the same orientation

relative to you. A map can be oriented visually or with a compass.

1.7.1 Visual orientation of a map

1. Observe at least two outstanding terrain features, such as two hills,

which should have an angle of at least 60° between them

(alternatively, the features can lie behind each other in a straight line,

relative to you).

2. Locate these terrain features on the map.

3. Turn the map until the map features and the terrain features are aligned

in the same direction relative to you — north on the map will now be

approximately aligned with true north.

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2.0 Using a Compass

2.1 Parts of a compass

The magnetic needle is divided into two halves, red and white. With the red halve

pointing to the magnetic north.

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2.2 North: True, Grid, and Magnetic

2.2.1 True North

True North is determined by sun readings and from the stars and is the

point we would call the North Pole or very top of the earth where all the

lines of longitude converge.

2.2.2 Grid north

North found on your topographic map. Map makers create a grid

system around every country called the National Grid. Each box on this

grid has a letter. It is this letter which we use to identify by means of a grid

reference our position on the grid. These grid lines are shown on our map

and are numbered thus allowing a grid reference to be created. As the

position of these grid lines are only slightly out of line with true north we

use them as our method of setting our compasses.

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2.2.3 Magnetic north

This is the north that is indicated on our compass. Magnetic north is the

location of a part of the earth which is magnetic and attracts the needle of

the compass. This north is located approximately north of Canada. (8

degrees west of grid north)

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2.3 Set a Map using Compass

Turn the map until the map magnetic north arrow points in the same direction as

the compass magnetic north, parallel to each other.

Note: If the compass magnetic needle, orienting and travelling arrow points

exactly north, you can use the orienting lines on both the housing and the base

plate to help set the map.

Compass Magnetic North

Map Magnetic North

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2.4 Back Bearing

A back bearing is the bearing in the opposite direction to your objective.

To calculate a back bearing

1. Take a map bearing or a bearing to a landmark, using a compass.

2. If the bearing is less than 180°, odd 180°.

3. If the bearing is more than 180°, subtract 180°.

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Conclusion:

To find the direct opposite side of the circle, the solution is to halve it.

Bearing 60° Back bearing = 240° (60° + 180°)

Bearing 295° Back bearing = 115° (295° - 180°)

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2.5 Determining your position on a map using a compass

2.5.1 Resection

Resection is a method for locating your position on a map with precision

by using a compass. It can only be used when at least two terrain features

can be observed which can also be identified on the map.

To find your position on the map, using resection:

1. Orient the map using the compass.

2. Identify two or three known distant locations on the ground and

mark them on the map.

3. Measure the bearing to the known positions from your location

using a compass.

4. Measure the back bearings of the known positions. Draw a line

for the back bearing on the map from the known position back

toward your unknown position.

5. The lines will intersect close to your position.

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Step 1:

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Step 2:

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Step 3:

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Step 4:

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Step 5:

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2.5.2 Intersection

1. Orient the map using the compass.

2. Locate and mark your position on the map,

3. Measure the bearing to the known feature.

4. Draw a line on the map from your position on this grid azimuth.

5. Move to a second known point and repeat steps 1, 2, 3, 4, and 5.

6. The location of the unknown position is where the lines cross on the

map. Determine the grid coordinates to the desired accuracy.

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2.6 Exploration with bearings

2.6.1 Line of Sight

Walk to an obvious landmark – a tree or boulder that is directly on the

bearing. Then take another bearing on the next obvious landmark and walk

to that. Keep it up until you reach your destination. By going to

intermediate landmarks, you minimize the chances of veering off your

bearing.

2.6.2 Aiming Off

It is almost impossible to walk a perfect bearing. In most cases your error

can be anywhere from 3 – 5°. This is known as lateral drift. Being off just

a few degrees can make a major difference after several miles. Therefore,

rather than head straight for your target, it is best to deliberately aim to

one side of your target (left or right). Then you will know whether to turn

right or left and walk to the target.

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2.6.3 Baselines

Baselines are helpful because they provide a large target to aim for. A

baseline is a reference line that lies across your course. It can be a trail,

cliff face, road, stream, or other feature. You can combine a baseline with

aiming off to help navigate. Find a baseline near your destination, and then

aim off of it. When you hit the baseline, you now know which direction to

turn to walk along the baseline to reach your destination.

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2.6.4 Walking around obstacles

When you reach an obstacle, the best method for maintaining your course

is to hike a rectangle around the object.

• Set a new bearing 90 degrees from your original heading and pace

until you have cleared the obstacle along that axis.

For example, if you original bearing was 30 degrees, hike a new

bearing of 120 degrees.

• Go back onto your original bearing, parallel to you original course

until you clear the obstacle.

• Set a bearing 90 degrees back to your original bearing (in this case

300 degrees) and walk the same number of paces.

• Now turn back to your original bearing. You will be along your

original line of travel.

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3.0 Glossary

Bearing

The angle between true North and the direction of your travel.

Chart

A marine map, similar to a topographical map, but showing details of the water, depths,

hazards and navigational aids. As a rule, charts show only very few features of land other

than the coastline and land based navigational aids.

Compass

A magnetic, mechanical or electronic device for determining the direction to magnetic

North.

Compass Rose

A circle, divided into 360 degrees showing the points of the compass, such as East,

North, Southwest, etc.

Contour Line

A curved line on a topographical map outlining places with the same elevation. It is used

to indicate steepness of the terrain.

Coordinates

A system by which you can determine your position. Most widely used systems are

Latitude/Longitude (Lat/Lon) and Universal Traverse Mercator (UTM). There are also

several other grids used, mostly by the military.

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Course

Intended direction of your travel.

Destination

The place where you are going.

Deviation

The change in the compass reading caused by the magnetic influence of the iron, steel or

electronics aboard a boat and its equipment

Global Positioning Satellite (GPS)

As system of 24 satellites orbiting the Earth and transmitting positioning information to

receivers on the ground.

GPS Receiver

An electronic device that automatically calculates your position from signals received

from the Global Positioning Satellite system.

Heading

Actual direction of travel.

Knot

Measure of speed expressed in nautical mile per hour. 1 knot = 1.85 km/h

Latitude

Measurement of your position expressed in degrees of an angle from the Equator. It is

measured 0 to 90° North or South

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Longitude

Measurement of your position expressed in degrees of an angle from the Universal

(Greenwich) Meridian and is measured in 0-180° East or West

Mile

Approximately 1.68 km

Nautical Mile

Approximately 1.852 km

Grid North

Though North is generally shown on maps at the top, the map may not be oriented

exactly to True North. The term Grid North refers to the North shown on the map’s grid.

If there is a difference between the Grid North and True North it is shown on the map

Magnetic North

A place in the Northwest Territories which is the centre of the Earth’s natural magnetism.

Every compass points to the Magnetic North pole, not to the true North pole.

True North

The actual (geographical) North Pole.

Originating Point

Place from which you started your trip.

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Scale

A measure by which you can determine distances from the map or chart. On a map in the

scale of 1:50,000, 1 cm on the map will correspond with 50,000 cm (or 500m) in the

terrain depicted on the map. On a map with 1:125,000 scale, 1 cm corresponds to 125,000

cm (2,500m or 2.5 km) in reality.

Topographical Map

An accurate land map showing great details and features of the land.

Triangulation

A method of determining your position by extending azimuths from your position to at

least 2 known features or points on the map.

Variation

Difference in direction between True North as determined by the Earth’s axis of rotation

and the Magnetic North determined by the Earth’s magnetism.

Way Point

A control point between from where you started and where you are going (final

destination). Waypoints are used to plot a course which takes turns and to check that you

are on the right course.

orienteering

Documents

map reading

map colors

map symbols

digit map grid reference

grid north

true north

magnetic north

table of contents1