Bearings
A bearing is a 3
digit angle measured clockwise from north. It is a way of indicating
direction without ambiguity. We usually speak of taking a bearing
between 2 points, or the bearing of the pub from the church. We may need
to use a bearing when the weather conditions are poor, or the
surrounding landscape is unfamiliar or featureless. Then navigating by
the map alone may not practical, and we may have to rely on the compass
to tell us the direction in which we wish to travel. You may also need
to take bearings when trying to pinpoint your position on the map by
triangulation. Either way the process is quite simple once you get used
to it. (Note: For accurate bearings you will need to take into account
the magnetic variation, but here I will ignore this for simplicity).
To take a bearing between two points follow these steps (again I will
assume we are using a common 'Silva' type compass). Note the two
alternative methods at steps 1 and 4.:
1. Leave the map as it is (in any old
direction) OR [Set up the map so that it is
facing north.]
2. Locate the point at which you wish to
walk from, point A, (i.e. usually your current location) and the point
you wish to walk to, point B.
3. Align the compass edge (assuming it is
rectangular) so that it forms a line between these two points. Note that
the compass should be facing in the correct direction (the direction of
travel arrow should be pointing towards the place you want to go, the
bottom of the compass is placed at your current location). If the
compass is not long enough to do this, use a ruler or similar to join
the two points and place the compass alongside this. The compass does
not have to have the direction of travel arrow touching the two points
(i.e. parallel lines will have the same bearing).
4. Rotate the dial so that the faint
vertical lines on the dial itself align themselves with the vertical
(blue) grid lines on the map OR [Rotate the
dial so that the red marker on the bottom of the dial matches up with
the red end of the north-south pointer]
5. You can now pick up the compass if you
wish. Read off the number on the dial against the direction of travel
arrow (there will usually be a small black marker to help you in this).
This 3 digit number is the bearing
of B from A. (Do not worry too much about the 3 digit business. If the
angle marked is 30° it should be called 030° but this does not really
matter too much). As always be careful about how many degrees each line
on your compass represents. There are many different types with
different markings, but usually each small line is worth 2° with
intervals of 20° marked on the dial in writing.
6. If you wish to walk in a straight line
from A to B, simply keep an eye on the compass and follow the direction
of travel arrow. You must take care to ensure that the two red pointers
(north-south and red marker on the bottom of the dial) remain aligned at
all times.
Important notes on using bearings
When following a bearing (i.e. attempting to walk in the
direction indicated by the compass) do not just try to look at the
compass and walk in a straight line. Even when trying hard to walk in a
straight line on flat ground there is usually a natural tendency to
deviate slightly (normally off to the right for right handed people) and
in any case, the landscape is hardly ever nice and flat. There will
always be reasons to deviate off your intended path, that clump of
trees, those holly bushes, that mountain spur. Even with flat ground and
good 'seeing' it is very tiring to continually check your progress
against the compass.
The best thing to do is to look along your bearing (taking care that the
compass pointers are aligned as best you can) and notice a landscape
feature that lays along that path (e.g. "that large gnarled oak
tree over there"). Then you can effectively forget about the
compass and just make your way to that feature along the best possible
root. Take regular sightings of the feature in case you lose sight of it
during your 'detours'. When you reach the feature, simply take the same
bearing again, (i.e. sight along the compass again) and repeat, looking
for a prominent feature. With practice this is a very quick, yet still
accurate method of travel. Of course it is not very effective in very
poor weather conditions, at night, or in featureless landscapes, and
there you will have to rely on regular (frequent!) checks on your
compass. But for most situations it is effective.