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Socorro Bouldering Guide - GPS Coordinates - UTM?

All coordinates in this guide are in UTM (NAD27). This is so you can find stuff easily.

UTM is Easy

For a person on foot, UTM is simpler and easier to use than Lat/Lon, and is usable even if you don't have a GPS.

UTM, or Universal Tranverse Mercator, is an x,y grid laid over areas of the earth. A UTM coordinate is simply meters East and North of an arbitrary point. For the purpose of finding boulders around Socorro, you and I don't care where this point is. All we care is that the numbers increase to the East and North.

If you have time and are curious, you can find a more detailed and technical discussion of UTM here or here. But this knowledge isn't needed to use the coordinates.

Let's look at an example:
Peck's Mystery Boulder: UTM 13S 0316489 3762020
If you're lucky enough to have a GPS, just set the units to UTM and you're all set. Make sure you're using NAD27 (GPS should default to this anyway). If you hate UTM, you can just change it back when you're done. All GPSs that I know of will convert tracks and waypoints to whatever unit system you have currently selected.

With UTM, You Don't Need a GPS

If you're like most boulderers, you don't carry a GPS. This is where the usefulness and simplicity of UTM for finding stuff on the earth really shines. For example, say you have found Peck's Mystery Boulder but want to find Fun Guy Boulder. You look up the UTM coordinates for each in this guide:
Peck's MysteryUTM 13S03164893762020
Fun GuyUTM 13S03165063762035
Difference (meters)1715

So, Fun Guy is 17 meters East and 15 meters North of Peck's Mystery. Go Northeast about 25 yards and you're gonna find it. Easy!

Why Not Lat/Lon?

I resisted the idea of using UTM initially, but many years of Search and Rescue groundpounding has beaten into me the clear superiority of UTM when navigating on foot.

Lat/Lon, or Latitude and Longitude, or sometimes inaccurately just called Degrees/Minutes/Seconds or Decimal Minutes. This system works wonderfully for ships and aircraft who cover big distances. For people on foot with no GPS, however, this system makes it very hard to find stuff. Even with a GPS, the grid is not paralell, meaning that Latitude and Longitude change at different rates. It is not an orthogonal x,y system, it uses spherical polar coordinates. Most people can easily use a nice square grid (orthogonal), but have trouble with a strangely curving one (spherical polar). In New Mexico, one degree of Latitude is about 17% longer distance than a degree of Longitude, but that changes depending on how far North you are.

If you really must use Lat/Lon, here are some utilities.

updated January 6th, 2010
Bob Broilo