The idiots guide to using a GPS, by the biggest idiot of them all...Roo.......
So you want sail fast...real fast. Not the usual BaFing (Backwards and Forwards) but real balls to the wall...off the wind sailing. If you're really serious...take a deep breath, clench your butt cheeks, turn the board at least 110 degrees off the wind, sheet in and hold on. Five hundred meters later you may be the new world speed record holder, but how will you know unless you've entered one of the three ISA speed contests to be held this year or there's a GPS receiver strapped to your arm. Glancing down at the screen if you see a number higher than 40 knots you know you're seriously quick, any less and you've got some work to do. That number on the screen is just the beginning, inside the GPS is a record of all your runs and, with careful analysis, the key to making you the Speedy Gonzalez of your beach.
Choosing a GPS is your first step. What you need is a unit that saves a track log of your runs and can record your position every second. You also need to ask yourself how serious you are about analysing and improving your speeds.
If you're a recreational sailor who just wants to take a few beers off your mates in informal speed contests then something like the Canmore GP-102 or GPS Logit app on a suggested smartphone is ideal for your needs. While the box it came in tells you its waterproof don't be fooled, you need an Aquapac to protect the GPS and keep the water out. The Paqua midi or an Aquapac is ideal, it comes with an arm band so you can strap it onto your forearm or bicep and watch the speed as you sail. The Foretrex comes with a cradle for recharging the battery and downloading data via a serial port on your computer. If you have a newer PC you may need a Serial/USB adapter to allow you to download the track log. The Garmin is fairly old technology so has a built in error that varies your speed somewhat, over longer runs it averages out but for instantaneous speeds don't bet the farm on its accuracy. With recording set at 2 second intervals software analysis cleans up the data but there will be few spikes from falls, catapults and swimming that need to be removed.
If you've got Antoine Albeau in your sights then the new generation of NMEA recording GPS devices is the way to go. They keep a record of the satellites used to generate your instantaneous position, their level of accuracy and your Doppler speed (actual speed at the time rather than calculated later). The data can be verified and one day may even be valid for certifying a world record. The best unit available is the NAVi GPS, it has a slot for a SD card, the SanDisk make is recommended, to record all the data which can then be removed and plugged into a computer for analysis. Like the Foretrex you will want to put it in an Aquapac, the larger Pro Sports seems to fit best. These GPSs are the most accurate available, and provide data you can rely on. The development of their use and software to analyse them was done in the US by the author and has been tested extensively around the world. For around $300 you can get a kit with the GPS, Aquapac, SD card, USB SD card reader, USB cable and car charger.
Once you made your runs, scared yourself silly, and bagged bragging rights at the pub from your speed readout on the gps screen, it's time to download the data and analyse your performance. There are a couple of free programs available designed for just this function. Uploads to Gps-speedsurfing.com and KA72.com can be used to transfer your data to GPSTC but you will need to register and log in.
If you've made it this far you'll find the following step by step guide handy for setting up your GPS before you head off to the beach for the first time. There's a few simple things to remember, make sure your battery is fully charged before each session, turn it on at least 10 minutes before sailing so it can lock onto all the satellites in your area and check to see the unit is switched on as you step into the water.