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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**

**13S** -
*Zone* - you can safely ignore it when using this guide.
**0316489** - *Easting* - East coordinate, in meters (one meter is about 10% more than one yard or about three and one-third feet)
**3762020** - *Northing* - North coordinate, in meters

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:

| | East | North |

Peck's Mystery | UTM 13S | 0316489 | 3762020 |

Fun Guy | UTM 13S | 0316506 | 3762035 |

Difference (meters) | | 17 | 15 |

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 6^{th}, 2010

Bob Broilo