Jubilee Centre BEL Course Notes
[Map Reading] [Grid References][Scale] [Contour Lines] [Setting the Map] [Taking Bearings] [Distances] [Getting from A to B] [Route Planning]
Navigation falls into two parts:
Map reading - Looking at a map and making sense of it, understanding the information and forming a picture of what you should be seeing.
Everything else! - Using a compass, your eyes, and common sense. For more advanced navigation we can use step counting, estimating time or specialist equipment like altimeters and GPS.
Maps use symbols called
conventional signs to represent roads, buildings, paths etc..
Every map has a key showing them, so you do not need to know every one, but
it is a good idea to familiarise yourself with the ones you need most.
E.G. Footpaths, bridleways etc. and the difference between them and say a
boundary line.
An understanding of contour lines helps to build up a mental picture of where
you are and what to expect on route.
They tell you the shape and height of the land, how steep it is, whether you
are going up or down, if you are due to arrive at the top or bottom of a cliff.
Also shown on the map is scale, numbered grid lines, magnetic variation and
the date the information was compiled for the map.
Ordnance Survey maps of the British Isles have a grid of numbered line, these are used to refer to points on the map - a grid reference.
Each of the squares is one square kilometre.
To give a more accurate position we imagine each square is further divided into tenths.
Sample Point: Tring Station
First Quote Eastings
Locate first VERTICAL grid line to LEFT of point and read LARGE
figure either in the top or bottom margin or on the line itself. 95
Estimate tenths from grid line to point. 1
THEN QUOTE NORTHINGS
Locate first HORIZONTAL grid line BELOW point and read LARGE
figure either in the left or right margin or on the line itself. 12
Estimate tenths from grid line to point. 2
Sample Grid Reference for Tring Station 951 122
This figure represents a square with 100 metre long sides, with the maps we use this is as accurate as we can get.
To remember which
way to go:
Go through the door ALONG the hall before going UP the stairs.
If you totally forget, the instructions are printed on the map.
When reading a map,
you learn to relate the information shown into a picture of what the landscape
will look like.
The two most widely used scales for walkers are 1:50 000 and 1:25 000.
What does it mean?
1:50 000 means 1mm
on the map is 50 000mm on the ground.
Therefore 1mm on the map is 50 metres on the ground.
1:25 000 means 1mm
on the map is 25 000mm on the ground.
Therefore 1mm on the map is 25 metres on the ground.
As you can see there
is more room to put in details on a 1:25 000 map, so this is the preferred
scale to use, but always be sure which scale you are using.
A quick and rough guide for estimating distance is using the grid lines, they
are one kilometre apart whichever of the two scales you are using and approx.
one and a half kilometres across the diagonal.
These are light brown
lines showing vertical height, and are usually at 5 or 10 metre intervals.
Every 5th line is thicker to make counting easier and is marked with the height
above sea level in metres.
The space between the lines help to build a picture, the closer the lines
are together the steeper the gradient is. With practice you build up a picture
of your route, plan to avoid steep ground, get an early warning when you go
off route.
If you find it difficult to tell if a slope is going up or down, a simple
guide is the numbers showing height are always printed to read the right way
up when looking uphill.
Getting the top of the map pointing North.
Using Landmarks - if you recognise landmarks and know where you are, you can line the map up with the features and get your map pointing North.
Using a Compass -
Keeping the compass flat with the needle pointing North, line up the map underneath
with the vertical grid lines in line with the NEEDLE and your map is pointing
roughly North.
You can then check details on the map with what you can see, e.g. church on
left, bridge over river in front, woods in valley to the right etc.
Map to landscape - which way to go.
Hold the map flat, place the compass with the direction of travel arrow pointing the want to go, and the long edge running along an imaginary line from where you are to your destination. ESTIMATE THE BEARING. Now turn the housing until the orienting lines are parallel to the vertical grid lines and the red arrow pointing to the top of the map.
Read the bearing, this is a GRID bearing.
Because the compass
needle points to MAGNETIC NORTH we need to ADD the magnetic variation.
Landscape is bigger than the map so MAGNETIC bearing is bigger than GRID bearing.
Hold the compass flat, turn around until the red arrow in the compass matches
up with the way the red end of the needle points, the direction of travel
arrow now points at your destination.
Grid to Mag - ADD
Map is smaller than the landscape so make bearing bigger
Landscape to map - where am I
To find out where
you are or to identify a feature.
Hold the compass level, face and point the direction of travel arrow at the
landmark, keeping the compass steady, rotate the housing to make the orienting
lines parallel to the needle - letter N to the red end.
Read the bearing, this is a MAGNETIC bearing, change it to a GRID bearing
by taking off the magnetic variation, remember the landscape is bigger than
the map.
Mag to Grid - RID
Landscape is bigger than the map so make bearing smaller
Place the compass
on the map, line up the N to the North of the map, the orienting lines parallel
to the vertical grid lines, line the long edge with your known position it
should now run towards the landmark, enabling you to identify it.
You can also use this to find out how far along a ridge you are, using the
same method take a bearing of the landmark, line the edge of the compass with
the landmark, line up the orienting lines with the vertical grid lines, draw
a line in pencil, if you are on a path or a ridge, where the line cuts across
is where you are.
In open country you can repeat this procedure with another landmark to give
a cross showing where you are.
When walking on a bearing, don't just look down at the compass, spot a feature along the bearing, walk to it, get another fix, another feature, leapfrogging across the countryside.
The easiest way to
gauge the distance of objects is a visual estimation, this take practice,
a good habit is guessing how far things are, and then checking this against
the map, by doing this you will get more accurate at this quick and easy method.
A quick reference from the map are the grid lines one kilometre along a square,
approximately one and half kilometres diagonally across the square.
Keeping track of how far you travel is important, for finding paths, changes
of direction, avoiding hazards/dangers.
There are two methods used - Time and Pacing / Step Counting.
There are set formulas
for keeping track of distance covered in a certain time, these can also be
used during planning for working out how long routes will take.
A good starter for groups is 3kph plus I minute per 10 metres climbed.
3kph works out at 2 minutes for 100 metres.
Small groups usually travel faster than large groups.
Make a timing card to save mental arithmetic in the cold and wet.
Pacing / Step Counting
Keeping track of the
number of steps you take, this is normally done for double steps, so every
time your right foot steps, you count.
You need to have a starting figure, usually the amount of steps you take to
cover 100 metres, from this you work out the steps needed to cover the distance
to the next landmark. Finding a method where you don't lose count is vital.
With practice, pacing and timing can provide extremely accurate aids to navigation,
enabling you to cover unknown ground in very poor conditions safely.
" Set and thumb your map.
" When taking bearings guestimate the answer to prevent 180 degree error.
" Use line features as handrails to guide you.
" Attack Points - easy to find near where you want to be.
" Collecting features - obvious feature telling you that you have missed your target.
" Aiming Off - deliberate error so that you know which way to turn for your target.
" Have a short description of the route in your mind so that you can spot route finding errors as soon as possible.
Take in detail as you walk, it will help relocate if you do get lost.
The most direct route
is not always the best. Sometimes it is better to walk around a hill taking
a longer flatter route than climbing over the top.
When selecting routes a few things need to be considered:
Obstacles - natural
ones like cliffs, rivers etc.. Manmade ones like private land, fences etc..
Type of ground - marshes, steep hills, exposed hilltops and ridges etc..
Would a longer route on paths be better than crossing open country.
Landmarks - churches, woods etc. that can be used as guides on the route.
Will you be able to see your landmarks or will they be hidden by intervening
terrain.
Contours - the more you cross, the more climbing / descending you will have
to do.
Get the big strenuous climbing done in the morning when the group is fresher.
Make a route plan, with details of distances, direction, approx. time allowed to cover the distance, with escape plans in case of a change in circumstances, weather, accident, group too tired etc.