• Rich Pyne

Maps, Compasses and GPS Part 2

Updated: Nov 28, 2019


Maps are great, and we are fortunate enough to have the best mapping in the world here. The database that the Ordnance Survey have is the largest in the world, and did you know that modern map making started in Scotland? Contours were “discovered” on Schiehallion.

Once you understand how the map relates to the ground, you can them see the image in 3D, and it is now very simple to follow. There are many different types of maps available, but I will just concern us with the standard recreation maps that we use in the UK.

The most common that everyone is familiar with is the maps produced by the Ordnance Survey. All of Britain is covered by The Landranger or Explorer Series.

Ordnance Survey Landranger.

These have been around for a very long time. The scale is 1:50,000 (1cm=500m, or 1mm=50m). The contours are every 10m above sea level, with the thicker Index Contours at 50m. All roads and rivers are on them, but only the main foot paths are there. If they put every detail on this map, you wouldn’t see the shape of the ground as it would be so cluttered. These maps are wonderful for longer journeys, like the Pennine Way, or in the winter mountains where things like paths are buried anyway!

Available in paper or laminated.

Ordnance Survey Explorer.

These have been around nearly as long. The scale is 1:25,000 (1cm=250m or 1mm=25m). These are designed for use by everyone, including surveyors.

The contours are still every 10m above sea level, with the thicker Index Contours at 50m intervals. Everything that is on the ground is represented on these maps as there is generally room for the detail. Every established path is there.

Paper or laminated versions.

These marks are fantastic for learning navigation, for harder navigation legs, and route planning. The downside is that if you want to walk in the Central Lake District, you may need all 4 maps!

Harvey Maps

These are a little different to The OS ones, with the most notable difference being the heights of the contours…Every 15m above sea level, and the thicker Index Contours at 75m. This does unclutter the map, but makes it more fun to workout time needed to ascend slopes using Naismith’s Rule (Add half a minute for each 10m of height gained, or in this case, 45 seconds). One feature that the Harvey maps have over OS is the coloured contours…brown for earth and grass, grey for rock, making it easier to see the 3 dimensions to the untrained eye.

These are also printed on plastic, so they cannot rot…Mine have been in the washing machine too (Inadvertently!)

Specialist Maps.

There are plenty of varieties if these around, but are quite specific. Basically, they are sections from established maps, sold under licence from the OS.

An alternative to these is to cut up a map you already have into manageable sections…No point carrying a huge map, you have enough to carry!!!

Mapping bought from t’Internet.

With the modern age of computers, it is very simple to obtain mapping for pretty much anywhere. This can be more cost effective than buying paper maps, allowing you to print what you need. One thing you can lose home printing is the fine detail that is produced on a bought paper map…Look at the difference through a magnifying glass. A printed one is often blurry, whereas on an OS printed one, each paper fibre can be seen without any blurring.

Tips, in no particular order…

If you walk in a group, always have more than one person navigating. If there is any discrepancies between the navigation legs, you have a good chance to work it out before wasting time and energy by walking in the wrong direction!

The National Grid System used for giving coordinates is a useful feature for sharing locations with others, namely in a Mountain Rescue situation. You don’t have to worry too much about the first 2 letters to put you in the right 100 square KM area, just give them your basic Grid Reference and tell them which map you are using.

All OS maps come with cardboard covers, which is only packaging… carefully remove it to make refolding the map much easier, and less of a squeeze getting it into your pocket.

Laminated or plastic maps are the way forward in my opinion. Well worth the extra money if it’s an area you go to often. They last a very long time, and you can draw routes on them, which can often be wiped off with the right substance (Not rain, that would be unhelpful!)

If you go to lots of different areas, then get the paper maps, and a good, waterproof map case. Ortleib seem to make the best ones, certainly the most reliable ones I have had. They seal with a few rolls at the top, the plastic is quite malleable, and does not ”yellow” with age. There are cheap map cases around, but they usually leak and/or crack... The most interesting designs I have seen had holes punched through them for a cord, a very clever idea that(?)

Do not store or carry compasses near batteries or magnetic fields. This can reverse the polarity of the compass, making it point in the opposite direction. Mobile phones is the obvious one, but what about the batteries in your lamp, or trying to take a bearing with your walking pole dangling underneath?

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