Flashes of Panic

JM asked about GPS receivers for “newbie” geocachers, which I don’t really have a good answer for, since I’ve only ever used one. (And practically wore it out, actually.) It happens to be a Magellan Meridian Gold (Garmin and Magellan (Thales Navigation) are the dominant companies in the field,) but I think you can do pretty well caching with any GPSr which has some of these qualities:

1. It’s hand-held. You’re not getting far with the GPS in your car.
2. It should resolve to thousandths of a minute of arc. (First you’ve got degrees, then minutes, which are sixtieths of a degree, then seconds, which are sixtieths of minutes. However, most caches show coordinates as XX° YY.YYY, that is, degrees plus five significant figures of minutes.)
3. You should be able to store twenty or thirty waypoints. (Waypoints are coordinates used to mark a location, so you’ll set waypoints for caches you’re hunting and then use the GPSr to navigate to that waypoint.) Like digital cameras, the more the better: I tend to fill mine with a few hundred.
4. It should easily connect to your computer so you can upload/download waypoints.
5. It should be easy to find out the coordinates of where you are now, your heading (the direction you are or have been moving,) and the bearing to the cache (which direction it is from where you are.) It’s particularly useful if it shows a compass dial with heading and bearing indicated; then you can just follow the arrow.
6. It should be easy to edit waypoints. (Waypoints downloaded from geocaching.com have an altitude of 0, and if the cache is a few thousand feet up, that introduces some lateral error; if I’m having trouble with a cache, I’ll frequently “fix” the altitude of the waypoint to get a little closer.)

In general, higher price brings two things: better reception (a more sophisticated antenna—GPS signals are weak) and/or better battery life. I do pretty well with a pair of AAs in mine, as long as I remember that plugging it in to the car jack automagically turns on the backlight and I need to turn it off when I unplug.

The geocaching.com website has a buyer’s guide which is nearly as general as this list. Among other things, they mention base maps; a good base map will keep you oriented to major roads nearby (mine lists most numbered state routes,) state parks, major mountain summits, etc., and a really good one will include more detailed topographic information. I’ve been supplementing my in-memory base map with topo maps I print from National Geographic Topo!; I can merge waypoints into the maps, so I’ve got a pretty good idea where I’m headed, at least in the part of the country I have CDs for. I’m not the only one, either; I’ve found Topo! maps that other cachers have left in caches. There’s one cacher near Boston who works entirely from topo maps, aerial photos, and other resources to locate caches without a GPSr.

Of course, once you’ve found the first stage of a multi, the map is of limited use. And now that I’ve explained how to select mid-range consumer electronics in order to leverage billions of dollars of military satellite technology for the purpose of finding hidden tupperware in the woods, I think my credentials as a raving geek are pretty much indisputable.

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