Designed for the serious performance sailor but simple enough for the casual boater The SPEEDWATCH wireless system brings real-time boat speed, trip log and distance information as well as a countdown and race timer to the dingy sailor with the convenience of displaying this performance data on your wrist. A choice of SPEEDWATCH impellers are included and can be attached to the transom or hull of the boat. The transmitter mounted inside the hull picks up the data and sends it wirelessly to the wrist-mounted SPEEDWATCH. Provides: Boat speed (through water) Trip log Race timer Countdown timer Red backlight Multiple impellers supplied Wireless transmission through hull