My cousin is a fell runner, and for his birthday a load of us are clubbing together to get him a GPS-type watch.

I've seen what looks like a good'un, but it says it gives a position of where you are in latitude?longitude format, based on the Greenwich Meridian, degrees, minutes, etc...

...is that the same as the usual map ref, 6 or 8 figure grid ref?

Nope.

... won't be a lot of good then, will it?!

Oh well, cheers for that - back to the drawing board!

No!

Ordnance survey grid references are an artificial construct unique to Great Britain which have no connection with latitude and longitude. Most GPS receivers can be tuned to OS grids but you should check to make sure.

OS maps do actually have latitude and longitude marked round the outside but I'd wish you luck if you were going to try adding the required (slightly curved) lines to your maps so as to be able to navigate using them.

However, I would imagine that every GPS available for sale has an option to display OS grid co-ordinates. Check the product details.

Some watches indefinitely support the required datum and grid for OS mapping.

Suunto do, however, you need to enable it using the Suunto PC software, presumably the datums can't all be stored on the watch so the software loads the appropriate one into the device.

Might also be worth mentioning that the manual for the Suunto X9 talks about battery lengths as low as 4 hours when the GPS is being used which makes them impractical for a lot of people.

My suggestion would be one of the garmin forerunner GPS wrist units, which dependant upon the model would include a HRM. I have the 305 which has that function. It won't give you OS GB grid co-ords but it does have a very useful function that allows you to backtrack your route and you can download your route at the end of the day to maintain an online training log. Battery life is around 14 hrs and it recharges via USB through your computer.

Paul: What is an HRM?

Heart Rate Monitor

Thanks!

Before you look at the Forerunner 305 it might pay to check out the reliability issues.
My friend is on his third, another got her money back after the second unit failed ( both lasted less than a week) You may be lucky but a google search will reveal that there are many who have not been lucky.
Another friend has an original Forerunner (105?) which is still working flawlessly so it might be a case of Garmin trying to cram too much technology into one unit.

Hugh, considering you are such an expert on fitness I'm surprised you didn't know what a HRM was. Pretty standard term in the fitness world.

Nice one Harry - another thread killed.

Harry: I am not, nor have I ever claimed to be, an expert on fitness but I can diagnose dyspepsia.

Devion,

Noted about the reliability issues, also having checked its the 301 I have with the 305 being the new model. I'm obviously one of the lucky ones as is a friend of mine who has the 101 that runs off AAA batteries. The older model can sometimes lose track of the gps signal in dense woodland or built up areas. You can pick up the older versions for a fraction of their original price if you shop around