Map Reading & Navigation – Part 8

Throughout this series of blogs covering Map Reading and Navigation we have dealt purely with the map and compass.  The reason for this is very clear, if you cannot use a map and compass you should never go into the hills, even in the most popular areas.

The clear, sunny day can turn bad very quickly and the ill trained and ill prepared will suffer, become lost, get injured or hypothermic, or worse – walk off of the edge resulting in a catastrophic fall.  This is not panic or rumour mongering – this is fact!


However, in the 21st Century, there are electronic devices which can help and assist us.  Note my choice of words, they do not replace the map and compass, they are used in conjunction with the same.  All of the devices I will discuss here use the Global Positioning Satellite systems or GPS.

At the moment there are two global positioning systems – NAVSTAR which is owned and administered by the USA (referred to as GPS), and the Russian GLONASS (Global Navigation Satellite System).  At the time of writing (2019) the European system, Galileo, is undergoing testing and evaluation as was the Chinese system BeiDou.


What I am going to discuss now is one device and two smart phone Apps.  These are not the only ones available, but are the ones that I personally use.  I will look at the handheld GPS device (in my case a Garmin Map64) and the Ordnance Survey’s smart phone App’s OS Maps and OS Locate.  Other brands are available for purchase or download.

GPS Device

A GPS device is a stand alone handheld SatNav, it allows us to navigate using downloaded routes and positional information from the GPS Satellite clusters.  To calculate position and track movement, a GPS receiver must be receiving information from at least 3 satellites. Altitude can be calculated if 4 or more satellites are in view, Generally, a GPS will track 8 or more satellites.


A GPS is capable of giving you your speed, heading, track, trip distance, plus distance to next waypoint or final destination.  It can have a typical accuracy of 10 metres


garmin-gpsmap-64Routes can be planned using commercially available software, such as Memory Maps or the Ordnance Survey OS Maps.  Once complete these route can be transferred as a GPX file to your GPS device and superimposed on whichever map standard you have purchased for the device.

In general GPS devices come with open source mapping software which is usable in most environments.  Alternatively you can purchase mapping licences from the Ordnance Survey giving you access to their extensive range of 1:50k or 1:25k maps.

Once all loaded up, the device can be used to give you a bearing and distance to your next way point, as well as an estimated lapse time.  However, always check and ensure that the bearing is not taking you into a dangerous situation, such as across a steep-sided gully!

garmin 3 pic
Selection of Garmin Map64 Pages

Over the years, I have found my Garmin MAP64 to be very accurate and has allowed me to navigate safely in poor visibility.  However, every move is always taken with reference to a paper map.  Accuracy of a GPS can be degraded when walking in dense woods or a narrow steep-sided valley where access to the satellites is restricted.

OS Maps App

246x0wImagine having access to every single 1:25k, 1:50k, 1:250K and 1:1M map produced by the Ordnance Survey (OS) on your PC, tablet, Android or I Phone.  Well that is exactly what you get with the OS Maps App.

The main difference between this software and something like Memory Maps software, is that this is web side based rather than device side based.  What this means is that everything is stored on the OS servers so once you have planned a route on your PC at home, you can then access from any other device.

route SS.jpg

For me the biggest advantage is that the maps are constantly being updated by the OS, so I have access to the latest maps.  I have the use of in excess of a million routes produced by others.  It allows me to use the route and the relevant section of OS map on my smart phone in the same way as I would use my GPS device.

I can download the route and the relevant section of map into my phone in case no network is available.  Before leaving home I am also able to print out an A4 or A3 section of the OS map with the associated route and route card.  If I use water proof paper, then I have an indestructible map.

image courtesy of OS Leisure

Other elements I have access to, include aerial photographs of the terrain over which I am walking, and all of the UK’s green spaces. On the PC and Tablet it allows me to do a 3D fly through of the route using actual aerial photographs laid over the 3D mapping matrix.

3d Fly through SS
3D Fly-Through with Augmented Reality selected

More recently Augmented Reality has been added.  This allows me to hold phone up to the horizon and the names of surrounding hills and mountains are highlighted on the screen.  The other great advantage is that as technology allows, more facilities are being added to the App and made available to all subscribers.

OS Locate App

locate-icon-febThe final application I am going to discuss is OS Locate.  This is not an App that you would expect to use all of the time, but one that could prove to be very useful.

On opening up you have a page which gives you information directly from the GPS satellites.  The most important of these is your position in National Grid Reference or Latitude & Longitude.  In addition you also have an electronic compass and an altimeter.

Screenshot_20190323-204639_OS Locate

Why is this important?  Simple, it does not require your smart-phone to be connected to a network to give you your position.  If you have got lost and need to relocate then this will put you within 100m of your actual position (error of a 6-figure grid reference).

This App’s importance is so well established that Mountain Rescue Teams have asked lost callers to download the app and give them their position.  you can also share this position via text message, to the emergency services, 999/911, (providing you have registered your mobile number with them in advance).



As I highlighted at the beginning, these are not an alternative to a map and compass.  They are to be used in conjunction with traditional techniques.  They will make navigation easier, of that there is not doubt, but they are also dangerous.

Never rely solely on them.  Their batteries have a short life, especially the one in your smart phone.  The OS Map app plus all of the other apps you will have running such as social media and a fitness app, will drain the battery very quickly.

If you are using a GPS device, always take extra batteries with you and if you are using your smart phone then please invest in a power Pack.  This is a spare smart phone battery that you can tap into when the power is getting low.

power bank

Please embrace the modern technology but never loose sight of the skills required to navigate properly with Map and Compass – safe journeys.

In Map Reading & Navigation – Part 9, we will be looking at other training resources and what courses are available.

Page 7   —   Page 9



2 thoughts on “Map Reading & Navigation – Part 8

  1. Pingback: Map Reading & Navigation – Part 7 – Hill-Walking For The Over 60's

  2. Pingback: Map Reading & Navigation – Part 9 – Hill-Walking For The Over 60's

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