THE PENNINE
WAY
Start - Edale, England
2 7
1
M
I L E S
Finish -
Kirk Yetholm, Scotland |
HOW TO USE A COMPASS
A compass can be used in many
ways which allow you to navigate to and from set points using
bearings, work out where you
are, work out where you have come from by using back bearings and
estimate distance and time.
There are other functions of a compass also but these are the main
ones.
A compass has a magnetic needle
contained within it, designed to always point North. This can
then be used to accurately work
out direction very accurately.
Very basically to take a
bearing you need to know exactly where on the map you are and to know
where on the map you want to
go, and use the bezel of the compass to create a bearing. I will
explain in more detail using
the photograph of my compass as reference.
Click on compass for a better view
Start finding any map you
happen to have. This ideally would be an ordinance survey map but any
map including a road atlas will
be fine as long as it points north as straight up. In addition it would
be useful if the map had grid
squares drawn over it, which in the case of an ordinance survey map
can be used to create grid
references.
Find any place on the map you
want to imagine you are at, and them choose a second place you
would like to imagine going to
on the map. Ideally these need to be fairly close together and joined
by a single footpath, bridleway
or road.
Place the long straight edge of
the compass on the map as so to line up the two chosen locations.
You can use either edge of the
compass depending on what is best for you personally or for the
map. Hold the compass in
position on the map, HOLD THE MAP AND THE COMPASS
COMPLETELY LEVEL (this is major
cause of getting the wrong bearing), and do not let it slip
for the rest of the process.
Now look at the map and locate
the grid squares going across the map both vertically and
horizontally. The grid lines in
this case however are the vertically lines (the ones running from the
top to the bottom of the map.
Now look at the inside of the compass where the needle of the
compass is and you will see the
compass also has lines drawn in it. Two of these lines end up
drawing a Red Arrow which
points to the N position on the outer ring of the compass circle, and
points to the zero mark,
between 340 and 20 degrees inside of the compass. In addition notice
these lines start of as black
and change to red halfway along.
It is these lines inside of the
compass you need to line you with the vertical lines on the map. The
whole compass section can be
turned around, so that the lines also rotate around also. By doing
this you can line up the two
sets of lines, from the map and from the compass. Make sure that the
Red Arrow part points up to the
top of the map. If it is pointing down your bearing will be 180
degrees out!! This can be
easily done and something I have both done myself when cold, wet and
tired, when trying to get of a
mountain quickly, when the weather turned for the worse. So double
check that the Red Arrow is
pointing UPWARDS.
If it is pointing upwards the
two set of lines will naturally be lined up also. But again just check
that
the two sets of line are as parallel to each other as they can be. Even 1
degree out here over
1 mile will push you out by 28 meters.
Might not sound a huge amount now, but what if you
were in completely zero
visibly, in 70 mile an hours winds with horizontal driving rain and on a
compass bearing for 3 miles at
night. That little error would put you nearly 100 meters off your
target. I refer to these
conditions as this is what I was in 3 years ago, but managed using very
advanced compass techniques
(which you can only learn thorough hours of practice), to get within
5 meters of my target, a
mountain refuge hut I had decided to get to so sit out the storm. However
despite being within 5 meters
of hitting the target, I had to start a sweep search to find the hut. In
fact I found it by literally
walking into it, such was the state of the weather I was in. If I had been
100 meters out I would have
been in serious trouble, but by taking a little more time to get my
compass bearing right and then
following it religiously I found it.
Now we have the bearing we are
almost set and ready to go, but there is a little something called
magnetic
variation that needs to be accounted for. This changes slowly decreasing at
the rate of 1
degree every 6 years in England. In 1990 the magnetic
variation was 4.5 degrees, and therefore in
2005 it is now 2 degrees. However
everywhere has a slightly different magnetic variation, and so
you need to
consult a recent map with this information on it to work out what it is in
your area.
Whatever value you have in your
area, you need to add this to your current bearing. Therefore if
for example you have a current
bearing of 90 degrees (i.e directly East) and you find your variation
to be 2 degrees you need to
change your bearing to 92 degrees. To slightly confuse things, my
compass uses radians as it main
value, and not degrees. As there is 6400 radians in a circle, this
equates to me starting with a
bearing of 1600 radians, and having to add on 36 radians (as 1 degree
= approx 18 radians), to give
me a final bearing of 1636 radians. (If you want to be picky, yes, in
mathematics there are 'only'
6283 radians but in navigation this is now rounded up to 6400 to
standardize the value)
Radians are not the standard
method of navigating but if you are confident with a compass are
worth considering using as when
used correctly are more accurate, but can be very confusing if you
are not trained in there use.
Please be aware of this when planning to buy a compass and be sure
you get one you are happy with.
Finally
you can now take your compass off the map and hold it straight in front of
you, KEEPING
IT LEVEL, and rotate around
with it remaining straight out in front of you. The aim of this part is
to get the RED NEEDLE
inside of the compass to line up inside the RED ARROW, with the tip
of the needle, exactly over the
point of the red arrow. Once this happens the compass is showing
you the direction to go. So double
checking the compass is level, held to point directly in front of
you, and that the red needle is line
up over the red arrow, you are ready to follow your bearing.