A speed sensor for a ship, more particularly, a thin speed sensor which can be mounted in the hull of the ship and remain flush with the outer surface of the hull. The transducer assembly for the speed sensor is composed of two thin piezoelectric transducers mounted in a spacer plate that locates them...http://www.google.fr/patents/US5581515?utm_source=gb-gplus-shareBrevet US5581515 - Thin speed transducer sensor
