Complex sentence: There are already several companies that use ultrasound to prevent and deter growth of algae on ships and boats of varying size, although the US Navy actually discovered the effects of ultrasound on marine life in the 1950's, with the development of sonar on submarines.
Split into simpler sentences: There are already several companies that use ultrasound to prevent and deter growth of algae on ships and boats of varying size. The US Navy actually discovered the effects of ultrasound on marine life in the 1950's, with the development of sonar on submarines.