Three different speed sensors are available (all are retractable). A 10m (33 ft) cable is included with the sensor, with a water tight connector fitted just next to it. Log Mixer and Switcher For added reliability, two speed sensors may be installed symmetrically on the hull. Normally, speed is averaged over both sensors. If a sensor fails, only the remaining one will be used and the jammed sensor signal will be ignored. On Multi Hulls it may be necessary to measure boat speed (only) on the leeward hull. Sensor switching will then be automatic as a function of wind angle or heel angle.