Airmar CS4500 Ultrasonic ST850 Style Insert - CS4500-850

Airmar's revolutionary CS4500 makes cutting-edge speed sensing affordable. Instead of a paddlewheel, it uses ultrasonic pulses to collect echoes from small particles in the water as they pass under two transducers embedded in the insert. This transducer monitors the particles in their respective beams. As the boat travels through the water, both transducers 'view' the same stream of particles. Because it takes time for particles to travel between the two transducers, the aft transducer detects the particles later than does the fore transducer. By measuring this time lapse, the instrument calculates the boat speed.