How would you like to keep your boat's bottom free of unwanted growth electronically? Well, the Ultra system from Ultrasonic Antifouling reportedly does just that with a transducer attached to the inside of the hull that emits pulses of inaudible ultrasonic sound waves. These waves are said to be harmless to fish but disrupt the single-cell organisms that foul a hull. It needs constant power for maximum effectiveness, so energy consumption is a factor. But if access to shore power is limited, the system is available with a solar controller that'll regulate the power generated by solar panels. While not billed as a replacement for bottom paint, the Ultra system can reportedly enhance its effectiveness.