Maps with UTM grid + GPS with utm coordinates is all very good. MGRS is even better - ever heard of it? It is UTM for dummies. It is UTM coordinates, but you replace the biggest number with a letter code (which only changes every 100km) and round the last numbers off to 100 meters accuracy. This is plenty accurate for wilderness navigation, IMO.


Example: Take the UTM coordinates 34W 422460 7734002. The MGRS equivalent with 100 meter accuracy is 34WDC - 225 - 340. On my 1:50.000 map, the numbers 22 and 34 correspond to the numbers written on the UTM grid (which is a 1 km grid). Those two numbers tell me which square I'm in, and the last digit ("5" and "0") tells me where I am inside that square. The 34WDC-part covers a 100- by 100 kilometer square, so it is straigthforward to keep track of that.

So instead of the 13 digits 422460 7734002 I only have to juggle around with two-by-tree numbers 225 - 340. MUCH easier! And much easier to add or substract in my head - I know instantly that my friend in position 236 - 443 is 10 km to the north and 1 km to the east (23-22=1, 44-34=10). Try doing that aritmetic in your head with 423649 7743928... Not to mention how hard it is to communicate all those numbers by phone, radio, SMS or email...

In the MGRS system, rounding off to 100 meter accuracy is optional. You can round off to kilometers, 10 meters or keep the 1 meter resolution (giving you the full coordinate 34WDC 22460 34002). But on a 1:50.000 map I can't read the coordinates with accuracy much better than 100 meters anyway, and 100 meters is PLENTY for my wilderness navigation needs. 100 meter resolution is the perfect compromise, IMO.

Please note that the GPS retains its full accuracy, it is just the resolution of the coordinates you see on the screen that's rounded off to 100 meters.


I've got a magellan GPS which was top of the range way back in 2004 (magellan meridian color). By today's standards, the map screen is horrible and the user interface is very primitive and little intuitive. But it has all the bells and whistles a geek can dream of, I can do any kind of map coordinates I like (I can even define my own, if I like) and the battery life (~15 hours) and accuracy is pretty decent, even with today's standards.

Today I'd go for a garmin, probably some model with "60" in it. But I would absolutely choose a GPS that can show MGRS with 100 meter accuracy.


Oh, by the way, both UTM and the MGRS (=UTM for dummies) is invented by the military.