-excerpt taken from www.westcoastultrasonics.net
Ultrasonic Anti-fouling is a safe and environmentally friendly alternative to using bottom paint that keeps boat hulls clean and free from marine growth. Cleaning and applying anti-fouling paint is costly, time consuming and more importantly, is toxic and unfriendly to the environment. The Ultrasonic System uses digital ultrasonic technology which emits sonic waves ranging from 19.08 to 41.66kHz in 14 bands with 200ns steps. When the control driver activates the ultrasonic transducers, which are attached to the inside of the hull, sonic waves/vibrations causes the hull to vibrate in tune with these pulses, making for a rather hostile and unpleasant environment for the marine growth.
This acts as a barrier surrounding the hull and the running gear and these sonic waves, which are attenuated after about 10 metres through water, kill off the algae cells and make it difficult for other such organisms to attach. By preventing algae growth on the hull, other marine crustaceans such as barnacles, molluscs, and limpets do not attach to the hull or running gear as not only is their food chain non-existent but the changing frequencies act to crustaceans as unwanted marine predators.