Presentation on theme: "Map and Compass A Scout’s Guide to Navigation A Woodbadge Project Les Unsworth (ASL) 1st Carrum Downs Scout Group September 1999."— Presentation transcript:
Map and Compass A Scout’s Guide to Navigation A Woodbadge Project Les Unsworth (ASL) 1st Carrum Downs Scout Group September 1999
By way of INTRODUCTION…...this “guide to navigation” is not intended to be a complete expose on what is an enormous subject and one on which you can find many excellent references. Nor do I pretend to be an expert on the subject. This guide was compiled to assist in the instruction of navigation and to improve my own limited knowledge of this important subject. Anyone who travels beyond the made roads needs to be able to read a map and use a compass. Navigation is often learnt by Scouts to earn badges. It is however a skill taught to enable Scouts to enjoy the outdoors by venturing beyond guided walking tracks and then find their way safely home again. This guide has been compiled from books, observation and experience, but most of all from what I have learnt from my fellow Scouters. Les Unsworth
CONTENTS Types of Maps Which Way is Up? Is North Really North? Scale Grid Lines and References Contour Lines Symbols How to Orient a Map MAPS COMPASSES What is a Compass? Parts of a Compass. The Points of a CompassThe Points of a Compass. Using a Compass. What, No Compass! EXIT
Maps a pictorial representation of the surface of the earth, as a whole or in part. Different types of maps are made for different purposes. These include world maps which show the positions of land, seas and oceans, Aviation Maps used by pilots, road maps for finding our way to a country town and street directories to help us find a friends house. Each of these work well for their intended purpose but are of little use on a 3 day hike in the wilderness. On hikes we need to know where we are at any time, where we are going, and how we are going to get there without having to cross a raging river or climb a dangerous cliff face. There are no street signs to help us, but there are landmarks such as hills and lakes. Topographical or contour maps, in the appropriate scale, particularly when combined with a compass are ideal and essential for hiking in the bush.contour maps TYPES of MAPS C
CONTOUR MAP C
WHICH WAY IS UP Before we can use a map we need to know which way it goes. Sure, you turn it so that the writing is up the right way, but are you facing the right way. Is that cliff in front of you or behind you? Is the camp to your left or your right? Getting the map the wrong way up in relation to where you are could mean getting lost or walking kilometers out of your way. By convention, the maps are usually drawn with north at the top and should have a North Pointer (usually an arrow ) to confirm this. If you turn the map so the pointer is facing North you will be looking at the map the right way around. This is called “setting” or “orienting” the map. More on this later. C
IS NORTH REALLY NORTH? C What is North? -Is it where the North Pole is found? - Is it the direction the compass needle points? - Or, is it the direction the vertical grid lines on a map? Yes, that right, North is all of these, but they’re all different. True North is located at the point in the Arctic region about which the Earth rotates. The Earth’s core is molten metal which gives off a field of energy much like that of a magnet. The magnetic poles are slightly offset from the Earth’s axis. The needle of a compass points to these poles, this is called Magnetic North. In Victoria Magnetic North is about 11 o east of True North. The grid lines on a map are parallel to each other but the Poles are single points. If these truly pointed to North they would not be parallel. Given that maps used for hiking cover a relatively small area (compared to the total surface of the earth) parallel lines suffice. This is called Grid North. Again topographical maps have pointers showing each of the Norths specific to the area covered by the map.pointers
IS NORTH REALLY NORTH? C S N Geographical North Pole Magnetic North Pole N
IS NORTH REALLY NORTH? C T.N. G.N. M.N GRID MAGNETIC ANGLE 10 O 21’ GRID CONVERGENCE ’ MAGNETIC DECLINATION ’ EAST TRUE NORTH, GRID NORTH AND MAGNETIC NORTH ARE SHOWN FOR THE CENTRE OF THIS MAP. MAGNETIC NORTH IS CORRECT AT 1988 AND INCREASES AT A RATE OF 03’ ANNUALLY.
SCALE C On maps everything is drawn much smaller than it is in real life. In order to keep things in proportion the maps are drawn to scale. If a map was drawn full size the scale would be expressed as 1:1, every 1cm on the map would equal 1cm in real life. If the map was drawn half size the scale would be 1:2. On a world map 1cm may equal 450km. There are 45,000,000cm in 450km, therefore the scale is written as 1:45,000,000. A road map might be scaled at 1:100,000 where 1cm=1km. The smaller the number the larger the scale and the more detail the map can show. Topographical maps of 1:25,000 (1cm=250) or 1:50,000 (1cm=500m) are used for hiking. The scale will be written and drawn on the map as illustrated here.
Maps are covered in fine parallel lines running from top to bottom and left to right at regular intervals. These are the GRID LINES. There spacing is regular and is specified on the map usually 1000m (1km). The grid lines can be used to identify a position on the map. Grid References are given as a 6 figure number. The first 3 digits indicate a position from west to east (Easting). Find the line immediately to the left (west) of the location and read the 2 digit number from the maps border. The 3rd number is obtained by dividing the space to the next grid line into tenths. The second 3 digits (the Northing) are obtained in the same manner using the lines running across the page and the line immediately below (south of) the location. The hill peak on this map is at Ref’ GRID LINES & REFERENCES C Grid Lines
CONTOUR LINES C Contour lines are brown in color and represent the shape of the landform at regular increases in height (usually 10 metres). The contour intervals are located near the maps scale. To help further some contours have a number indicating it height. The line either side will be 10m higher or lower. The closer the lines are to each other the steeper the slope. This is illustrated on the following pages. Remember that maps are flat, 2 dimensional representations of the earths surface. This is fine for road maps, but for hiking we need to know the shape of the land as well as its layout. Topographical maps do this with contour line. MORE
CONTOUR LINES C MORE
CONTOUR LINES C
SYMBOLS C In order to put as much information as possible on to a map, symbols are used to represent features such as roads, buildings, fences, swamps, forests and lakes. To further aid the map reader, many symbols are colored. A legend illustrating and identifying the symbols will be found on all quality maps.
HOW TO ORIENT A MAP C BY INSPECTION Study your surroundings and find a prominent land mark (2 are better). Find the landmark(s) on the map. Turn the map until the landmark, the corresponding symbol on the map and yourself line up. Your map is now oriented. - If 2 landmarks were used, your location is the point on the map where the 2 lines cross. BY COMPASS Place the map on a flat, level surface, Place the compass on the map near the direction pointers. Turn the map until the “Magnetic North” pointer and the red end of the compass needle are aligned. The map is now oriented. Adapted from the Scout Fieldbook
DIY WHAT IS A COMPASS? C A compass is a simple device used to indicate the direction of North. Consisting essentially of a free moving magnetised needing which aligns itself to the earths magnetic lines. As discussed elsewhere the compass needle points to Magnetic North rather than True North (the geographic North Pole). This difference is referred to as Magnetic Declination. (Please refer to the Maps section). Several types of compasses are made. Base plate compasses such as the one pictured are ideal for bushwalking, orienteering and working with maps.
PARTS OF A COMPASS C Direction of Travel Arrow Ruler Orienting Lines Orienting Arrow Lanyard (Carry Cord) Transparent Base Plate Index Pointer Graduated Dial (in 2 o Steps) Magnetic Needle (North end is red) Magnifying Lens Rotatable Liquid Filled Compass Housing With Graduated Dial and Orienting Lines
POINTS OF THE COMPASS C North South EastWest The Cardinal Points The 8 Principle Points
POINTS OF THE COMPASS C North 0 0 South East West The 8 Principle Points North East 45 0 South East South West North West
HOW TO USE A COMPASS (Following a Bearing) C Rotate the compass “dial” until the bearing (degree or direction) is aligned with the “Index Pointer”. Hold the compass on the palm of your hand as level as possible so that the needle can move freely and with the “Direction of Travel Arrow” facing straight ahead of you. Turn (yourself and the compass) until the red end of the “needle” points to “N” The “Direction of Travel Arrow” is now pointing in the direction of the bearing. Look up and straight ahead into the distance. Pick a landmark that the Direction of Travel arrow is pointing towards. If you walk towards this landmark you will be following your bearing.
WHAT, NO COMPASS ! If you venture beyond that guided walking track mentioned in the introduction, you will of course have a compass with you. Won’t you?! But what if an accident occurs and your compass is lost or broken? Here are two simple methods for getting your bearings. Click on an image to find out how C
DIRECTION USING YOUR WATCH C
1. Point the 12 toward the sun C
DIRECTION USING YOUR WATCH 1. Point the 12 toward the sun 2. Imagine a line mid way between the 12 and the hour hand C
DIRECTION USING YOUR WATCH (Approximate) NORTH 1. Point the 12 toward the sun 2. Imagine a line mid way between the 12 and the hour hand 3. This is approximately the direction of North. C
DIRECTION USING YOUR WATCH (Approximate) NORTH 1. Point the 12 toward the sun 2. Imagine a line mid way between the 12 and the hour hand 3. This is approximately the direction of North. Note: Allow for daylight savings!! C
DIRECTION USING YOUR WATCH (Approximate) NORTH 1. Point the 12 toward the sun 2. Imagine a line mid way between the 12 and the hour hand 3. This is approximately the direction of North. Note: Allow for daylight savings!! C DIGITAL WATCH ?
DIRECTION BY THE STARS You may not be aware of it but the stars, if watched for long enough, appear to revolve across the sky in a clockwise direction. The centre of their path (in the southern hemisphere) is the South Celestial Pole. If we can pinpoint the South Celestial Pole, we can find south. We do this by using the SOUTHERN CROSS. C Photo: Star Trails - The South Celestial Pole Jarrad Unsworth. Sept.1997 Hattah-KulkyneNP Vic.
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 1 1. Locate the Southern Cross in the night sky. Horizon C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 1 1. Locate the Southern Cross in the night sky. 4 Times length of Southern Cross Horizon 2. Draw an imaginary line through the length of the cross, extending four times it’s length. C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 1 1. Locate the Southern Cross in the night sky. 4 Times length of Southern Cross Horizon Due South 2. Draw an imaginary line through the length of the cross, extending four times it’s length. 3. Directly below the end of the line is Due South. C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 1 1. Locate the Southern Cross in the night sky. Horizon Due South 2. Draw an imaginary line through the length of the cross, extending four times it’s length. 3. Directly below the end of the line is Due South. 4. Or imagine a line through the Pointers and another at 90 o from it’s centre. Below where this and the line from the Southern Cross intersect is Due South Pointers C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 1 1. Locate the Southern Cross in the night sky. 4 Times length of Southern Cross Horizon Due South 2. Draw an imaginary line through the length of the cross, extending four times it’s length. 3. Directly below the end of the line is Due South. 4. Or imagine a line through the pointers and another at 90 o from it’s centre. Below where this and the line from the cross intersect is Due South Pointers C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 2 Achernar 1. Locate the Southern Cross and Achernar in the night sky. C METHOD 2
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 2 Achernar Pointers 2. Draw an imaginary line between the Pointer closest to the Southern Cross and Achernar. 1. Locate the Southern Cross and Achernar in the night sky. C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 2 Due South Achernar PointersHalf Way 2. Draw an imaginary line between the Pointer closest to the Southern Cross and Achernar. 3. Due South is directly below the centre of this line. 1. Locate the Southern Cross and Achernar in the night sky. C
FINDING SOUTH BY THE SOUTHERN CROSS METHOD 2 Due South Achernar PointersHalf Way 2. Draw an imaginary line between the Pointer closest to the Southern Cross and Achernar. 3. Due South is directly below the centre of this line. 1. Locate the Southern Cross and Achernar in the night sky.. C
WHAT NEXT? Practice C EXIT
Thank You C EXIT
WHAT IS A COMPASS? DIY Compass in a Cup C 1. Magnetise a needle by stroking it with a magnet (in one direction only) times, 2. Balance the needle on a leaf or a piece of cork floating in a cup of water. 3. The needle will align itself with the Earth’s magnetic poles. 4. Use a real compass to identify the north end of the needle
Aim: The aim of this precis is to provide a stand by means of finding True North for those ill-equipped ‘navigators’ who are frequently in need of inspiration but rarely at loss for excuses. Step One: Find the sun. This is done by looking skyward when a blinding glare, often accompanied by pain in the eye, will indicate the direction of the sun. Alternatively, look at the ground (to find ground, see step two) and find your shadow. Then, keeping yourself upright align the tip of your shadow (SH) with the top of your head (H) and slowly turn H through 3200 mills to look along the line SH-H-Sun. Step Two: Shadow Stick. Find a straight stick and place it upright in the ground (to find ground, look immediately below your feet where ground will normally be parallel to and continuous with the soles of your boots). Note that stick (S) will cast shadow (SH) on the ground (G) Step Three: Clock Face. Refer to digital watch and ensure that time shown is correct by either (a) checking with conventional watch owners nearby, or (b) when out in the bush, by dialing 1194 from nearest telephone. Then, by having established the time of day, draw on ground (G) a conventional clock face around stick (ST) using ST as pivot for clock hands not normally shown on digital watch. Onto representational watch face drawn in the hands of conventional watch at correct time of day as per digital watch. Step Four: Aligning Clock Face. Align the figure 12 on clock face with sun (S) by rotating ground (G) around stick (ST) until figure 6 coincides with shadow (SH) to achieve the alignment 6-SH-ST-12-S. Step Five: Find North. Draw a line on the conventional clock face from pivot (P) to a point mid-way between 12 o’clock (12) and the hour hand (H). This line, P-(12-H) should indicate North. If in doubt, firmly close your eyes and spin around until you feel dizzy and fall down, whereupon rising from the ground (G) there is at least a chance that you will be facing North (N). Finally: If all else fails. Remove digital watch from your arm and swing it around overhead AND LET GO. Your digital watch will then have ‘Gone West’ in which case True North is probably over your right shoulder. Instructors Note: Finding North by digital watch is to be regarded as ‘confidential information’ and should only be taught to scouts advanced in map reading. North by Digital Watch