Ultrasonic antifouling grows as ‘green’ option for vessel owners
by Susan Buchanan,
Introduction by Susan Buchanan
By using sound waves, ultrasonic antifouling can prevent the growth of algae, barnacles and slime on boat hulls and interiors, and can protect sea chests and box coolers as well. The technology has been employed internationally from Europe to Australia, Japan, Chile and the Caribbean, and implemented on commercial, military and recreational vessels. More recently, these systems have caught on with yacht owners in North America. Fouled, rough hulls can slow boats and increase fuel consumption, and antifouling paints — while effective — can release toxins when a vessel is in the water or when coatings are scraped off in dry dock. Usage of ultrasound has grown following the International Ultrasonic antifouling grows as ‘green’ option for vessel owners by Susan Buchanan Maritime Organization’s ban over a decade ago on organotin in bottom paints, and because of moves to limit copper as an antifouling agent. Ultrasonic systems don’t rely on chemicals that can harm fish and mammals or pollute the air, and they can reduce vessel liftouts for cleaning. The cleaning abilities of sound waves have been recognized since before World War II. Starting in the 1950s, sound waves were utilized for this purpose in the food, agriculture, electronics, medical, aircraft and auto industries. While ultrasound’s marine applications have been acknowledged for decades, usage by commercial vessel operators has only gained traction in the past 15 years. To install a system, transducers are trends & currents Courtesy U.S. Coast Guard www.professionalmariner.com 37 antifouling can keep weeds, barnacles and mussels away without hazardous chemicals, cathodes or paints, (and) with no expensive lift-outs, scraping, high-pressure cleaning or the subsequent disposal of poisonous wastewater.” Impressed current antifouling (ICAF) systems typically use a copper alloy rod to prevent fouling and an aluminum or ferrous alloy rod to reduce corrosion, along with a power unit. Introduced to the market in 2008, NRG Marine’s Sonihull systems produce multiple pulses of ultrasonic energy in a range of targeted frequencies. These pulses are transmitted through the material to which the mounted inside a vessel’s hull, or on other internal features, along with a control box. Onboard generators or shore sources power the equipment.
Susan’s interview with delta-sistems’ Chiel de Wit:
For commercial users, the most common application of ultrasonic antifouling is protecting sea chests, bucket strainers, box coolers, intakes and piping for dry plate cleaners, said Chiel de Wit of delta-distems BV in the Netherlands. “In smaller vessels, we can also protect the hull,” he said.