In reply to tom_in_edinburgh:
> Let's get real. A device that tells you exactly where you are to within a couple of metres is manifestly superior to one that tells you roughly which way you are pointing.
Get real yourself. You could, for a start, compare like with like: position and direction are two different things. If you don't understand that properly then you're not really qualified to lecture others about navigation IMO.
> It's arguable whether GPS has already made compasses redundant or whether it will make them redundant in a few years but it is clearly an overwhelming superior technology.
GPS is a
positioning technology (the clue is in the name). If you want to know which
direction you're pointing you need something that references a fixed directional datum, such as the Earth's magnetic field - ie that which we call a "compass". Many handheld GPS devices do have an electronic compass built-in to augment the GPS (though the eTrex 10, for example, doesn't) and most modern smartphones so too. But it is fundamentally still a magnetic compass, albeit one with an electronic interface, and it's still subject to the same vagaries as any other magnetic compasses eg false readings caused by rock with a high ferrite content such as are found in the Cuillin.
A GPS-only device can only report your heading if you are moving - it does that by "looking back" along your track. If you are stationary then the best it can do is tell you the direction you were last moving in. Even small amounts of positional imprecision over time are enough to undermine that approach, since the unit will think that you're moving about in random directions. The effects of this shouldn't be underestimated: for example, even when I'm standing stock still my Garmin 310XT usually tells me that I'm wandering about at anything up to 5kph.
> The second question is whether a digital map is superior to a paper map. Again it's arguable about whether digital maps have already made paper maps redundant but there is little doubt about what will win in the end.
Evidence, please, for this lack of doubt? Plenty of people on this thread have raised doubts. And why does it have to be about "winning"? Why can't both co-exist, as they do now?
> Having all the maps you need with you at all times without wasting pack space
How many maps do you need? The OS used to cover the whole of the West Highland Way at 1:25,000 with just two maps. Harveys now do it at 1:40,000 (which should be plenty for a waymarked route like the WHW) on just one map. Most day walks only need one map, or two if the map boundary is in an awkward place. Even three or four Landranger maps is hardly a significant weight, no worse than a GPS with backup batteries (and maybe a backup GPS, just in case?)
It's pure fantasy to imply that without a mapping GPS everyone used to stumble around with half the OS maps for the UK in their rucksack.
> having the map set automatically and displaying your position on the map are all compelling advantages.
A lot of your arguments are based around the advantages of a device which integrates positioning (GPS), heading information (compass) and digital mapping. It's true that the result is convenient, and an argument could be made that reducing the task loading involved in the largely mechanical processes of locating yourself on a map reduces the risk of mistakes in stressful situations. Equally, though, there are undeniable disadvantages to being overly reliant on electronic equipment in remote areas which should not be lightly dismissed.
I often do carry a basic eTrex GPS when I'm out in the hills. Most of the time I carry it simply to record my route for later reference, but I don't have any compunction about using it to re-orientate myself if I think it's necessary - and if I think it would actually be quicker than just looking around me and engaging my brain a bit more firmly. I also have a smartphone with the Viewranger mapping GPS app on it, though I have yet to bother trying to use it out in the hills since a paper map (usually a photocopy of the relevant A5-sized section of the paper map, with the full map stashed safely in my rucksack as a backup) has been more than adequate for me to date. If I found myself having to rely on the phone for navigation I'd be extremely concerned about battery life. Batteries do run down: it's inherent in their function, unless you never actually turn the device on!