The marine GPS receiver in its purest form is meant to answer three important questions: Where are we? What direction are we going? How fast we are going? For the philosophical navigator, the answers to the first two questions may be the most intriguing, but for the Melges 24 racer bound for the finish or the Caribbean cruiser hoping to drop anchor before sundown, the digits beside the word "knots" are much more compelling. So it should come as no surprise that a new breed

Mounted on the mast of a 1974 O’Day Javelin, the Velocitek SpeedPuck (above) shows a maximum speed over ground of 45.7 knots (reached on the highway while trailering).

of GPS devices—appealing directly to our need for speed—are making steady inroads into the sailing market. …