It’s probably worth taking two minutes to explain about my GPS navigation device. As usual I have gone for something a little different, a little bespoke.
I use Memory Map for route planning. This is a Windows PC application for which you can buy many different OS maps – these are provided by Ordnance Survey and look exactly like a paper OS map, just on the screen of your PC. Country Walking and Trail, both use Memory Map in their published routes each month. I have most of the UK National parks in 1:25,000 scale and all the UK in 1:50,000 scale.
Routes you create in Memory Map are shown as a blue line and walks recorded by the GPS are shown as red lines (see screen shot).
Memory Map comes with a version of the product for use on a Windows PocketPC compatible PDA (handheld computer) and as I have had various PDA’s over the years it was an easy step to install MM on the Pocket PC. My PDA is an iPaq hx4700, which has a fantastic high resolution screen and comes with a Compact Flash memory slot as well as a Secure Digital memory slot.
Recently it has been possible to get GPS receivers which will plug into a Compact Flash (CF) slot in a PDA, meaning that the PDA has full GPS capability, through a communication port provided by the CF slot. These GPS cards are available on ebay for as little as £30, however my initial experiments with this cheap card were less than satisfactory, so in the end I spent a little bit more and bought a branded receiver from a well known manufacturer. This works brilliantly, it gets a satellite lock very quickly and maintains it under difficult conditions. It even works in the house!
Putting all these elements together, I have a high resolution screen in the palm of my hand showing a 1:25,000 scale OS map with my current position pinpointed. If I have produced a route in Memory Map and transferred it to the PDA I also have a blue line overlayed on the map showing the route for the day. As I walk a red line is written to the map recording the current speed, height, time, position etc. This is called a track.
When I start walking, the GPS extrapolates the movement and produces a red line (which varies in length depending on how fast you are walking), pointing in the direction of travel. This is similar to taking a compass bearing, because in itself GPS cannot display a compass bearing.
When this is enclosed in a waterproof case such as those produced by Aquapac, I have an electronic substitute for paper maps. Generally this system is deadly accurate (to within 10 yards) and makes navigation so much more simple. Not least I am free from having to fold my map (or worse still change maps) several times a day.
It is not a fool-proof alternative to a map and compass though, battery life is limited and instead of changing maps mid-way through a walk I generally have to change batteries instead. If disaster strikes I always carry the appropriate OS map in my pack along with a waterproof map case.
Update: The case shown above is the old version supplied by Aquapac and to be honest, was always a little too small for my PDA. They now do a much better case (called the “Small Whanganui“) which is longer in the body and has a clearer case. This can be found on their web site, here. At the time of writing, this case was £15, inc. VAT and delivery.
Update #2: Advances in GPS devices has meant that it is now possible to get a GPS device that will fit into the SD card slot of a PDA, this makes them much smaller and lighter and also compatible with a wider range of PDA devices, as you no longer need a CF slot