E-Tech Yachting’s NRG ultrasonic antifouling system has had its effectiveness put to the test after a busy year of use onboard 34m Nautor’s Swan build, Anemos. The system was first installed at the beginning of 2011, to supplement the pre-existing paint-based antifouling, but it was only when the German Frers-designed yacht was hauled out in 2012 for wintering work that E-Tech’s system could be rated.

The yacht’s chief engineer, Duncan Nutt, wholeheartedly approved of the system, claiming that its installation typified the term ‘plug and play’ whilst the results amounted to “no evidence of barnacles on the underside and only slime, which is easily wiped away.”

Nut said that this served to greatly reduce running costs:

“Divers are expensive these days but it’s far easier for them to go down there and wash away surface slime than use the machines required to remove [fouling].” “Ultrasonic antifouling will have undoubted benefits for racing yachts, where hull aerodynamics are key. It certainly makes it easier to move through the water if there is nothing in the way,” he added.

The E-Tech system.

Multiple transducers are installed in the hull. The transfer rate of the ultrasonic signal is much higher on steel than fibreglass and therefore most effective. However, the system works and has been proven on all hard surfaces. On commercial ships each transducer should be calculated to a 3-5m radius on steel hulls to obtain ultimate results.

The Anemos hull as it's hauled out.

The NRG ultrasonic antifouling system utilises the latest digital electronics and ultrasonic transducer technology, by producing multiple bursts of ultra sonic energy simultaneously in a multiple range of frequencies. This energy produces a pattern of alternating positive and negative pressure. The alternating pattern creates microscopic bubbles during periods of negative pressure and implodes them during periods of positive pressure in a phenomenon known as "cavitation." The implosion creates a micro-jet action that not only provides the cleaning effect on the hulls surface below the water line, it also resonates and destroys single cell organisms such as algae. The removal of the initial link in the food chain inhibits the growth barnacles and other marine life that feed on the algae.

As well as reducing hull damage and maintenance costs, E-Tech also claims that the success of the antifouling system improves the aerodynamics of the hull, therefore enhancing fuel efficiency.

Upon seeing the hull, Captain Richard Foster was pleased with the results:

“I can only think of positives when it comes to commenting on this system! A friend who had it fitted on his boat in Dubai recommended it to us, so we had some track record to base our decision on. The major convincing factor in favour of us fitting [the E-Tech system] was the results from installation in the middle east, where there are serious growth problems due to warm water temperatures.”

Would he continue using it and recommend it to others? “Based on these results a I would say a resounding yes” said Foster. “Before [E-Tech’s system] was installed the bottom would have to be physically cleaned by divers twice in a season. And the yacht’s performance is noticeably and consistently improved due to having a clean hull.”

Captain Richard Foster.

Related Links

E-Tech Profile | E-Tech Website

Nautor’s Swan Profile | Nautor’s Swan Website

German Frers Website

If you have enjoyed reading this article, you’ll love our upcoming event, The Superyacht Design Forum, taking place on 25 - 26 June 2019 at Design Centre, Chelsea Harbour. The Superyacht Design Forum provides anyone in the superyacht design world with a unique opportunity to explore new thinking and share smarter solutions for the future of superyachts. To find out more or to register, click here.