INTRODUCTION
- Orienteering is about using a topographic map and compass to find points in the landscape.
DISTANCE MEASUREMENT
- Need to know the scale of the map (usually provided at one corner of the map)
- Straight line distance can be measured using ruler (if available) or marking out using paper and compare it to map scale.
- Curved distance can be measured using a piece of string and compare it to map scale.
- To measure actual distance travelled on ground, we use the technique of pacing. There are 2 types of pacing, single step pacing (counting every stride) and double step pacing (counting every other stride). Do enable us to use pacing, we need to know how many strides we need to take to complete 100m, before employing the technique in orienteering.
SHAPE OF THE GROUND
- Relief is a general term applied to the shape of the groud on a vertical plane.
- There are two distinct elements in the representation of relief, 1) representation of height and 2) representation of shape.
- A common example of relief is contour.
i) A contour is a line joining points of equal height and is the standard method of showing relief on topographical map.
ii) Contours are shown at a regular interval (ie difference in height between successive contours are the same), which varies according to scale of map and type of country mapped.
iii) Contours are usually drawn as continuous line and every fourth or fifth contour is called an Index Contour.
iv) When spacing of contours down a slope gets closer together at the bottom, the slope is convex. When spcing of contours gets further apart at the bottom, the slope is concave.
v) Irregular and closely spaced contours indicate rugged and broken slopes. Smooth contours indicate smooth slopes.
MAP REFERENCE
- All topograhic maps are usually divided by lines called the grid lines. Vertical grid lines that numbered from the west to east are called the Eastings; horizontal grid lines that numberd from south to north are known as Northings.
- Map Grid Reference are numbers (from the combination of Eastings and Northings) given to identify points on the map. They can have 4, 6, 8 or more digits but always have even number of digits. The Eastings value always come before the Northings value and the point to be identified is located to the North East of the intersection.
DIRECTION
- Points of the compass
i) North, South, East and West are 4 cardinal points of the compass
ii) There are in all 32 prinpical points of the compass, but only 16 commonly used in map reading.
iii) The 32 principal points are (starting from North in clockwise direction): 1) N, 2) N by E, 3) NNE, 4) NE by N, 5) NE, 6) NE by E, 7) ENE, 8) E by N, 9) E, 10) E by S, 11) ESE, 12) SE by E, 13) SE, 14) SE by S, 15) SSE, 16) S by E, 17) S, 18) S by W, 19) SSW, 20) SW by S, 21) SW, 22) SW by W, 23) WSW, 24) W by S, 25) W, 26) W by N, 27) WNW, 28) NW by W, 29) NW, 30) NW by N, 31) NNW, 32) N by W, 1) N
- A bearing is an angle, measured clockwise, from the zero degree line (North).
- Back bearings are the opposite of forward bearings and differ by 180 degrees (addition or subtraction depend if forward bearing is smaller or bigger than 180 degrees)
- There are 3 types of Norths, 1) True North (direction of North Pole), 2) Grid North (parallel to Eastings) and 3) Magnetic North (direction compass needle will point when left undisturbed).
COMPASS
- The silva compass is the most common compass used in NPCC. It consists of the following parts:
i) Base plate
ii) Ruler
iii) Direction of travel arrow
iv) Index line
v) Orienting arrow
vi) Orienting lines
vii) Magnetic needle
viii) Compass housing with degree dial
ix) Damping fluid (prevents vigourous fluctuation of magnetic needle)
WALKING TECHNIQUES
- There are three walking techniques used in NPCC during orienteering to ensure accurate pacing to determine distance.
i) Walking on a bearing (Man to object)
ii) Walking on a bearing (Man to man)
iii) Detouring/Side-stepping
MAP SETTING AND FINDING POSITION
- Setting a map is to turn the map such that the details on the map correspond with the details on the ground. There are 2 methods of settin map.
i) By inspection
ii) By north
- To find your position on the map, there is also 2 different methods.
i) Resection
ii) Intersection
MAINTENANCE OF MAP AND COMPASS
- Compass
i) Do not bundle compass together
ii) Do not swing compass about
iii) Do not place compass near metallic objects
iv) Avoid dropping compass
v) Do not play around with compass
- Map
i) Waterproof map
ii) Map should be folded according to grid lines (necessary to fold for convenience, focus, as well as to prevent it from crumpling due to strong wind)
