So you've heard that it's cool to fly with a GPS. But what does it really do for you? Here is a list of some of the more useful things it does:
Current favorite models are the Garmin 12 and Garmin 76 (shown above). Older used GPS's, such as a Garmin GPS III, (which are a few years old now) are perfectly adequete. Models with a bigger display are easier to read while flying. (Especially if you are approaching age 45. ;-) Some units have more memory which is good for downloading detailed maps of specific areas. However, the base maps that they come with are very good. Be aware that the Garmin detailed map CD costs about $100.
Garmin is by far the most favored brand used by HG and PG pilots. They were the first ones to provide a map built into the units. A map is now a prerequisite. Don't buy a unit that does not have a map! One of the best features of the map is that you can easily radio a detailed description of your position to someone on the ground (such as your driver) while flying, even in somewhere you have never been before. This is a real help. The basic map that comes in a Garmin is very detailed, showing almost every road, river and lake in the entire USA. In addition, the maps cover the entire world (!), although in greatly reduced detail. If you plan to use the GPS outside of the US it is best to get one with plenty of memory so that you can download detail maps of those areas you will be visiting.
The GPS comes with a small metric screw hole in the back of the case. It is not difficult to bend up a simple aluminum sheet-metal mounting plate that will accomodate your vario and GPS together. Get the metric screw at the hardware store. Be sure to leave access for the battery and data ports if possible. If you don't feel comfortable making a mount call one of the major HG dealers or manufacturers for special mounting products.
One of the most fun features of a GPS is to be able to download your TrackLog into your computer and overlay it on a map. For this you will need the computer cable which is a bit pricey if you buy it from Garmin (about $35). If you are handy with a soldering iron you can get the parts to make one at this URL at a very low cost. To download the tracklog you need a free copy of the program Waypoint+, available here. You will also need to purchase a copy of DeLorme Street Atlas (which is a handy program to have on your computer for travel planning.) Waypoint+ guides you through the few steps to download your tracklog and then exports the tracklog in a format that DeLorme can read. It will create a detailed track on the map of your position every 15 seconds (or whatever recording interval of time you set in your GPS). When you zoom in you can actually see every turn of your thermalling circles (you can see this best if you set the GPS to store position every 10 seconds or less). Once you get the map on the screen you can get a screen print of it by pressing the Alt and PrintScreen keys together. Next go into a word processing program or a graphics program and Paste the image in. The result looks like this: