Event sensor

An automatic timing measurement system provides a measure of time of passage of a watercraft through a prescribed course. Inertial or other estimates augmented by GPS speed/position measurements are used to track the position of a the watercraft. Position estimates are used to allow the locations of prescribed courses to be mapped and memorized. The passage of a watercraft through mapped courses may be detected for the purpose of measuring and reporting time of passage of the watercraft past key points in the course, and for modifying the behavior of the speed control portion of the apparatus if necessary. A measure of accuracy of driver steering can be provided along with the ability to automatically steer the watercraft through the course. GPS speed control is augmented with a secondary velocity measurement device that measures speed over water resulting in an optional user selectable real-time compensation for water current.