| navigation a guide to traditional and electronic navigational aids and techniques |
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My first really long trek was along a footpath
which links Geneva with Nice. On the first day, I discovered that
the route was marked with red and white stripes, painted on trees at
regular intervals. Assuming that my map and compass were redundant,
I stuffed them away in my pack. Hours later and the trail I was on
bore little resemblance to the one described in my guidebook, but I
managed to justify to myself that what I was looking at really did
match the description. In the late afternoon, I descended to a road:
the book said I should have been climbing to a hut. I asked a local
person for directions. He gently explained to me that I had been
walking the wrong way for more than half a day. I subsequently
discovered that many paths in Europe are marked with exactly the
same stripes. Since then, I have always consulted my map and compass
regularly, regardless of how obvious the way ahead
appears. Cotswold stores hold a healthy stock of maps and navigational aids. So if you need a demonstration of how GPS works, or if you are looking for a particular map, just ask a member of staff. And watch out for those red and white stripes! Paul Deegan Paul is the author of the award-winning ‘The Mountain Traveller’s Handbook’, published by the British Mountaineering Council and available from Cotswold. |
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map reading |
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Navigating with a map and compass is often seen
as something of a black art. It isn’t. Perhaps one of the easiest ways to become familiar with reading a map is to buy a map of your home town. Once you have identified the street you live on, you will be able to trace familiar routes to the shops, railway station and local church in order to see how they are depicted on a map. By consulting the key, and learning the symbols for bridges, pubs, telephones, as well as important natural features such as boulders, outcrops and cliffs, you will quickly become acquainted with how a map relates to the reality on the ground. You might even learn some new things about the town or village you live in. Once you have got to grips with reading a map, you will be able to transfer your new-found skills to less familiar areas, as the principles remain the same. |
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Hand in glove with the right map goes the right
compass. On the face of it, all compasses do the same job: they
point towards magnetic north. But just like maps, there is plenty of
choice when it comes to choosing a particular model. If your only requirement is to orientate a map, then a button or small compass with a simple north-pointing needle will probably suffice. Indeed, some watches include digital compasses that can perform this task quite adequately. For more accurate navigation, and for taking a bearing, a larger liquid-filled compass with a baseplate is essential. A typical hillwalking compass will include many of the following features: |
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maps |
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Several manufacturers produce high-calibre
compasses that are suitable for use in the UK. However, as you move
around the globe, the compass needle will tilt up or down depending
on where you are. So if you are planning to visit several countries
at vastly different latitudes it might be necessary to buy more than
one compass, or buy a special compass that is designed to balance
correctly regardless of your location.
If you ascend to altitude, you might find that one or two bubbles appear in the compass housing. This is nothing to worry about and providing the bubble does not grow to dominate the whole housing, the dampening effect of the liquid will remain effective. Bubbles usually disappear upon returning to a low altitude.
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Almost every corner of our planet has now been
mapped, from Antarctica to Afghanistan. However, the quality of maps
varies enormously. Here in Britain we are blessed with very accurate
maps. All that you have to do is decide what scale of map is most
appropriate for your needs. Walkers and cyclists usually find that
1:50,000 (which means that 1cm on the map represents 50,000 cm or
500m on the ground) are quite adequate. For more detailed
navigation, a 1:25,000 scale map provides a huge amount of
additional information which can be extremely useful when crossing
unfamiliar country. In Europe and in North America the accuracy of maps is often comparable to that of the UK. But many other destinations have been poorly mapped. In these countries, the best bet is to try to obtain military maps, and some nations are now making these available to the public. However, you may have to wait until you arrive in-country before being able to get hold of them. If your local Cotswold store is unable to obtain the map you are looking for, you might want to contact our friends at these stores: Stanfords, tel: 020 7836 1321. www.stanfords.co.uk The Map Shop, tel: 0800 085 40 80. www.themapshop.co.uk |
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altimeters |
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gps |
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A map and compass - and the knowledge to use them
correctly - is all that is usually necessary to help you navigate
across a landscape. However, when you are ascending or descending a
slope, an altimeter is required to help pinpoint your position on
the map. Sometimes, an altimeter is essential. For example, when
descending a ridge in bad weather, a reading from an altimeter is
the only way to calculate exactly where on the arête you
are. Analogue and digital altimeters are available, but regardless of type they all function by working off barometric pressure. This means that the altimeter will be affected by changes in the weather. This is most commonly seen if an altitude reading is taken at the end of the day and again the following morning. Although you will have remained static overnight, your altitude will appear to have changed if, say, a trough of low pressure moved in. Changes can also occur from hour to hour. So whenever you come across a feature that has its altitude marked on the map, take a moment to adjust the altimeter in order to maintain its accuracy. Altimeters are manufactured with a maximum altitude ceiling. If you hike and climb in the UK and Europe, an altimeter with the minimum ceiling (typically 4000m) will usually suffice. If you venture further afield, to mountain ranges such as the Andes and the Himalaya, then a model with a higher ceiling (usually 6000m or 9000m) is worth purchasing. |
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and mariners are all benefiting from the Global Positioning System
(GPS) which comprises of 24 satellites that bathe the Earth in
accurate time signals. Handheld, affordable GPS devices weighing
just a few ounces receive information from satellites passing
overhead in order to calculate longitude, latitude and altitude.
Once the GPS device knows where it is, directions to other places
can be computed. Most GPS devices can present longitude and latitude as grid references which match a variety of countries’ mapping systems, including the UK’s Ordnance Survey. Some GPS models also have built-in maps, although these are currently more useful for drivers operating in urban areas than walkers heading into remote locations. Bear in mind that GPS devices rely on circuitry and batteries, which can make them vulnerable to damage in the outdoors. Also, because of the way that satellites ‘look down’ on the Earth, the altitude reading is rarely as precise as the horizontal measurement (which is typically accurate to within 10 or so metres). Bearing all these factors in mind, many people wisely use a small GPS unit as a superb back-up to and cross check for a map, compass and altimeter, rather than as a complete replacement for these traditional navigation devices. |
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safe & dry |
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using map & compass |
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There are times when your safety may depend on
the reliability of your navigation equipment. Therefore it’s worth
making sure that when you really need them, your compass, GPS and
other devices all perform as expected. Your first stop is likely to be a durable map case. A clear case that has a waterproof seal rather than a potentially leaky zip will help to prevent spots of water from penetrating the cover and slowly turning the chart to a soggy pulp. Alternatively, it might be possible to buy a waterproof map, or make your existing maps waterproof by covering them with Fablon. Pocket-sized sections of maps can also be laminated at a local print & copy shop. Some GPS devices are waterproof or water-resistant. Other models can be popped into a micro-version of the map case described above, allowing the unit to be used without having to be exposed to the elements. Compasses tend to look after themselves, but it is important that they are kept away from metal objects such as penknives which can pull the compass needle away from magnetic north. Finally, consider carrying a spare compass and map in case your main set are lost. And don’t forget to pack a spare set of batteries for your GPS. |
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After a short time spent map reading, you are
likely to discover that using a map on its own can be somewhat
limiting, particularly when navigating in bad weather or when you
need to travel from one point to another that cannot be seen with
the naked eye. In these instances, employing a compass will help you
to navigate without being reliant on what you can see. In short,
using a map and compass together is an essential skill that all
people who venture into the outdoors will want to
have. Fortunately, there are many books that explain how to navigate with a map and compass. A few useful titles (available through Cotswold) are mentioned below to help you on your way. Alternatively, you might want to hire a qualified mountain instructor to put you through your paces. Art of Outdoor Navigation. Hurn. (CD-ROM) GPS Made Easy. Letham. ISBN 0921102666 Mountain Navigation. Cliff. ISBN 1871890551 Safety On Mountains. BMC. ISBN 0903908271 Association of Mountain Instructors, tel: 01690 720314. www.ami.org.uk National Mountain Centre: Plas-y-Brenin, tel: 01690 720214 |
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lost & found |
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Even when you have learnt how to use a map and
compass, it is still possible to become lost. This can occur for a
number of reasons, from a mis-calculation to an error on the map. In
these circumstances, some people feel an almost overwhelming urge to
push on in the hope that things will turn out all right. But as I
illustrated in my introduction, taking this course of action can
easily make a bad decision much worse. It’s almost always better to
retrace one’s steps to the last known position and then try again.
This might cost you several minutes, but could save hours. If you do become hopelessly lost in poor visibility, then it might be better to sit tight rather than risk stumbling over the edge of a cliff. If you are properly prepared with proper clothing and a survival bag, your predicament is unlikely to deteriorate into a life-threatening emergency. Furthermore, if you have taken time to leave a note of your intended route with a responsible person then the fact you have failed to materialise at an agreed time should be reported by that person to the police. They will then request assistance from mountain rescue teams in order to begin a search. Of course, if you do make it off the hills to a place of safety, remember to call and let your contact person know you are OK! (Remember that on many mountains, including those in Britain, mobile ’phone reception is non-existent.) |
© Paul Deegan & Flirt Design under license to Cotswold Outdoor Ltd.