How Close Are You, Really?
We asked Alec Stewart, of Velocitek, about the accuracy of the GPS, and whether 6 to 10 feet was an acceptable fudge factor. He tells us that "in practice," WAAS GPS accuracy can be as good as plus or minus 3 feet in North America. Also, he adds, "because the ProStart is used to measure your position relative to the line, rather than your absolute global position, the accuracy can be even better than 3 feet when you first ping the line. This is because, on a global scale, your boat, the race committee boat, and the pin are all close together. As a result, the GPS errors in measuring your position, the position of the race committee boat, and the position of the pin tend to be similar in direction and size. This makes the errors cancel out when the ProStart calculates your position relative to the line.