Biofouling of underwater surfaces by marine organisms is prevented by irradiating the surfaces or the adjacent water with ultraviolet light and adjusting the intensity of the ultraviolet light so as to kill or temporarily stun marine organisms to prevent their attachment to the underwater surface....http://www.google.ca/patents/US5322569?utm_source=gb-gplus-sharePatent US5322569 - Ultraviolet marine anti-biofouling systems
