Iíd owned a GPS unit for about a year before I really had a chance to see what they were really all about. We were on a skiing trip to Mt. Shasta, and just for the fun of it, I carried a unit and logged waypoints as we climbed in perfectly clear weather. Throughout the day, the clouds that had started out in the valley crept up behind us until they finally engulfed us right at the summit. Visibility was reduced to zero and a trace of snow soon covered up our crampon tracks. Between the swirling white clouds and the featureless white landscape, vertigo was setting in and we were having trouble just standing up, let alone making it back down the mountain. With about two hours of daylight left, I switched on the GPS, we slowly retraced my waypoints back down a nondescript ridge. We were making slow but steady progress until one of the group took a 1,500í sliding fall down the wrong side of the mountain. Now we were in totally unfamiliar terrain, with zero visibility, an hour of daylight left, no bivy gear and we had a long climb just to get back to the ridge. Visions of snowcaves and a very cold night immediately came to mind. But, before admitting defeat, we were able to zoom out on the GPS display, get an idea of the big picture and evenutally work our way back up to the ridge and headed in the right direction. Fortunately, my GPS unit came with a backlit screen which was essential for navigating back in complete darkness. After a few more hours and a few thousand less feet, we walked right back to the 10íx10í platform where our tent used to be, but thatís another story.
Since then, Iíve used those same waypoints to summit Shasta in a complete white-out, have found gear stashes and trailheads in the dark, and preprogrammed routes and landmarks for areas that Iíve never been to before. For better or worse, once you are armed with a GPS, map and compass, about the only thing stopping you from getting from A to B is your own common sense.
GPS (Global Positioning System) units have come a long ways in the last ten years. The part you buy, the receiver, is just the tip of a massive array of orbiting satellites that send out time stamped signals, which your receiver uses to triangulate your position to within about 100í of anywhere on earth.
There are many industries that use GPS units (aviation, marine, transportation, etc.) and thus many different manufacturers, models and features available. For climbing, skiing and hiking, the units are roughly analogous to a cell phone in terms of size, cost and complexity. Easy to operate buttons are nice when you have cold hands or are wearing gloves. Another personal consideration is how many features and functions you are willing to learn and scroll through - more isnít always better when you are frustratingly lost. Most units are self contained with built-in antennas, a small display screen and are usually powered by AA batteries.
Ranges from XX to XXX but before you buy one, youíll need to decided what you are going to do with it. A smaller, simpler unit might be all you need for backcountry use, but not have enough features to help you navigate through Pittsburgh. Conversely, a high end unit might have built in maps, a full color screen and XX hour battery life, but will be too bulky to carry with you. As with most consumer electronics nowadays, unless you have some specific reason to go to the extreme high end or low end units, your best values are going to be in well established , high volume mid priced units.
If you are going somewhere that you need to carry a GPS, itís a safe bet that itís going to be more than 100í away from your car, in which case you will want to carry the lightest unit possible. While the differences in GPS units weight is equivalent to a carabiner or two, one way or the other, it is something to consider. Often times what causes a unit to be heavier than others is that it carries more batteries, which means longer life, which in turn might be worth the extra weight.
Size matters and small is beautiful in the world of GPS units. Ideally you should be able to carry it in a small camera type pocket on one of your pack shoulder straps, or in an easily accessible pocket. Quick access means that you will be able to take more waypoints and/or use it on a regular basis instead of having it buried in the bottom of your pack and only pulling it out when you are hopelessly lost.
This is a key feature when considering which GPS to buy. As it takes a few minutes for the units to power-up and acquire their satellite readings, turning them off and on can become a hassle. Conversely, if you leave them running, itís quick and easy to take a waypoint, but you run the risk of having the batteries die. Most, if not all, of the units have back-up batteries and memory so you wonít lose any of your information when your batteries die. A common strategy for a long trip is to only mark major waypoints, in which case 12 hours of operating life can be stretched to many days of navigating.
The current offering of GPS units all have a very usable degree of weatherproofing and will survive being dropped in the snow, some rain and having coffee spilled on them. In general, they wonít survive an extended swim in a lake. Better weatherproofing usually means a little bit beefier housing and some protective structure.
While GPS units are amazing by themselves, they are exponentially more useful when you can connect them to a computer. Programs such as the TOPO! waypoint manager allows you to download your waypoints so you can sort and save them on your computer and thus donít have to scroll through hundreds of them while you are out hiking. Cooler yet, many of the National Parks and recreational hotspots are available on CD-ROMs maps, which allow you to create routes and then download them to your GPS unit. This can be especially useful when you are going somewhere unfamiliar with notoriously bad weather. Most units have this capability, although you will need to buy an accessory cable and computer software to make use of it.
To the brains of a GPS unit, waypoints are precise East and North coordinates that describe a location on earth. To a climber, skier or hiker, a ďwaypointĒ is something like a trailhead, where you stashed your car, a fork in the trail, the location of a crag or a series of points on a featureless plateau. Waypoints are the most basic element of a GPS receiver and can be created manually, automatically or downloaded from your computer or the Internet. Most units hold at least 500 waypoints, which is a lot if you are creating them manually, but not excessive if you are automatically creating routes. Too many waypoints can quickly become unmanageable and youíll want to either delete them or download them to your computer.
Routes are clusters of waypoints arranged in sequential order. The advantage of following a route is that the GPS unit will take care of selecting the next waypoint and pointing you in the right direction. Some GPS units will automatically create a route from waypoints it generates as you as you hike along.
Since darkness is a main cause of getting lost (at least in my case), having a backlit display that you can read in the dark without a headlamp is a big plus.
If you are planning a traverse of Greenland, Antarctica or the Sahara Desert, operating temperatures will be important. As there are no moving parts to a GPS receiver, in moderately cold temperatures you will most likely notice a decrease in battery life before any other noticeable effects.
Auto Battery Shut-off
A blessing for those of us with short attention spans.
Number of Satellites
This is one of the most important features of a GPS units. Some older units will only pick up six or eight satellites, whereas the current standard seems to be twelve. Being able to pick up more satellites means more accurate positioning as well as faster acquisition updates. It also means better reception around obstacles such as trees and rock formations. In practice, you will usually get four to eight satellites, but that can be severely effected (cut in half) if you are standing next to a large rock wall, or are in a deep canyon that is blocking your reception.