In 2008, Darren Rowlands was in Greece and met a fellow sailor who had a boat in Dubai. He was tired of hauling it to clean growth off the bottom and he was searching for an alternative to copper-based, environmentally unfriendly bottom paint. Rowlands and the yachtsman came up with a plan to use ultrasound waves to kill algae.
“We knew it worked really well when the marina and mooring power was shut off during the heat of the summer and within four days, his boat had a meter’s worth of beard growing,” said Rowlands, who is the chief executive officer of SoniHull, a company that makes ultrasonic systems used to keep barnacles, mussels and other growth from attaching to a boat’s hull.
SoniHull launched at the Dubai Boat Show in 2009 and sold out. Then the company made its debut at the ensuing Southampton Boat Show, drawing interest from owners of boats ranging from 23 to 60 feet.
Since then, the company and other businesses have witnessed the concept of ultrasonic antifouling systems transform into a burgeoning industry. Each entity has its own take on the idea, but basically, they use transducers that transmit ultrasonic waves through the hull bottom out into the water to prevent growth. The systems don’t replace antifouling bottom paint, but complement it by extending the life of the coating.
“We knew they didn’t want to have to haul their boat every year,” said Rowlands. “If they could get it to two or three years, it was cost effective to buy the system.”
The Pioneers
While SoniHull started with recreational boats, Rowlands said the company’s customer base is 98 percent commercial and superyachts. But that doesn’t mean he doesn’t see the consumer business growing.
“People want a green technology,” he explained. “They want to use a hard coating and then they want an ultrasonic to delay the requirement of hauling a boat in the recreational world.”
SoniHull’s Echo system is targeted for pleasure boats and one of the highlights of the technology is that it is one of the least power hungry on the market, drawing 3.6 watts per transducer. It can be run off house batteries and doesn’t require a separate power source. A boat owner also can communicate with the system remotely via a smart phone. “We listen to what our end users want and create ways to support them,” said Rowlands.
Soni Hull also said that its transducers are different because they’re encapsulated in a protective composite, not a hollow tube. That translates into 98 percent of the ultrasonic waves exiting out of the bottom of the unit. The transducers are also IP68 rated for waterproofing, and Rowlands said, “They can’t be damaged and have no metallic surfaces.” The transducers attach to the hull with epoxy adhesives and, as with any transducer, if the hull is cored, the core material must be removed and the surface made solid.
If a potential customer is worried that the ultrasonic waves will damage a hull’s structure, Rowlands said it’s not a concern. “We normally operate between 90 and 50 kilohertz. You don’t need to overpower it,” he said. “It’s not about the power. It’s about the song you sing.”
All of the companies said that their systems are not a replacement for bottom paint. “We don’t replace a coating,” said Rowlands. “We add to it and that is extending the life cycle of the coating itself.” If a boat in Florida needs to have its bottom scraped by a diver six to eight times per season, the SoniHull Echo reduces that number to two or three times. “There’s a lot of issue about copper and the new paints don’t have the answer yet,” he added.
Initially, Rowlands said the split was closer to 50-50 between power and sailboats for customers. The benefits for a motorized boat are easier to see because the fuel savings make the return on investment simpler to measure. “Biocide-free paint isn’t doing the job it used to so you’re adding diving costs to that,” he said. “Having a clean bottom, the return on investment can be easily demonstrated.”
An Echo system consists of four to six transducers and a management system depending on the number of bulkheads and if the boat owner wants to protect his bow thruster and propulsion equipment.
For a 50-foot trawler, Rowlands estimates the cost would be $5,000 to $6,000 plus installation. “I’ve gone past the days of just specifying to win a sale,” said Rowlands. “We spec to ensure the success of the system.”
SoniHull is estimated to be on nearly 5,000 vessels around the world. The company has a research-and-design center in the Middle East and works with Warwick University in the United Kingdom.
For larger vessels, SoniHull, which has been in business since 2009, also provides antifouling for internal raw-water systems like sea chests and similar components.
Scotland-based Marine Growth Prevention Specialists also focuses on the commercial market with its Ultraguard systems. “We are one of the top two or three in the commercial shipping world,” said Chris Ryan, a co-founder of the company. “We have some five or six small leisure boats and we’re on quite a few superyachts longer than 50 meters.”
Marine Growth Prevention started by partnering with a Dutch company that was doing research on ultrasound systems for the commercial market. The system uses 120- or 100-watt transducers and Ryan said the company offers digital versions as well. “The electronics are fully digitized and how we control the resonance so we always get a pulse response. You can stick our transducer anywhere and it will always resonate.”
The company makes all the parts for the Ultraguard system in-house in a factory on the east coast of Scotland. The offices are on the country’s west coast.
Ryan explained that many people misunderstand how ultrasonic technology works. “People will say they produce the signal that makes the larvae of barnacles or mussels think it’s a predator so they don’t adhere,” he said. “The larvae try to find the perfect spot to anchor. If you’re able to create a high-frequency vibration, they can’t hold on so they float away.”
If a hull bottom or the inside of a pipe is full of growth, an ultrasonic system won’t remove them. It can only prevent them beforehand.
For a 60-foot boat, the system would consist of four transducers and Ultraguard packages are custom-designed for each vessel. Ryan says it works on metal, fiberglass and even carbon fiber. The company packages up to four transducers with a control box and the system can run on 12 or 24 volts. The Ultraguard Master Series was developed for the pleasure market. It retails for about $2,250 and it comes with a control unit, transducers, cables and sealant.
Ryan says the company has never had to replace a burned-out transducer. “They have a cyclic life in the millions, but we say 10 years for replacement,” he added.
The power requirement for the Master series is 24 volts/6 amps and the system has a sensor that will turn off if it doesn’t detect the required voltage. The control box is installed under a console and a technician can plug in for service. Otherwise, it is self-sufficient.
“It will never kill a battery so you’ll always be able to run accessories like your bilge pump,” said Ryan.
When Ultraguard first exhibited at the Southampton boat show, po- tential customers also were looking at Copper Coat bottom paint, which was more expensive.
Pleasure-Focused
While SoniHull and Ultraguard focus on the commercial market, Hull Shield was founded to serve owners of pleasure boats.
“Most companies concentrate on the workboat and commercial markets,” said Mike Mahaffey, chief sales officer, technical sales, OEM and commercial at Hull Shield. “We were the first successful company to get involved in the retail market. It’s more complicated than the workboat market because you’re dealing with many different boat construction types.” It’s easier to get a fat contract signed for a commercial client with a fleet of boats compared to selling a system to a boat owner.
Two other things set apart Hull Shield. The company is based in Mt. Pleasant, S.C., and its system is fully digital. “We don’t use a capacitor,” said Mahaffey.
“Our system runs cooler and is more reliable because capacitors don’t last as long in the marine environment. We don’t need to have fans in the box to cool it.”
SoniHull and Hull Shield also claim to be the only companies in ultrasonic antifouling to create their own waves. “It was a known technology developed by the U.S. government many decades ago and they didn’t do anything with it,” said Mahaffey. “In a magazine 20 years ago, there was an article and many companies copied that algorithm. We’re one of the two that we’re aware of that make our own waves.”
Hull Shield offers two systems, the HD, for boats up to about 80 feet long and the HDX for larger yachts and commercial applications. Hull Shield systems are a supplement to antifouling paint. “If anyone says they’re a replacement, they’re not properly explaining how the technology works,” he said.
Mahaffey said that Hull Shield customers can expect to gain one to two years between having to replace bottom paint. “In Florida, if an average client has a diver come every two to three weeks, we take them to having a diver come two to three times per year,” he said. “When you have a cleaner hull, you’re saving fuel and there is less environmental impact. When you’re scraping paint, you’re releasing paint particles into the water. Any reduction in that is a win-win for everybody.”
Hull Shield’s website is set up for an individual to buy easily. HD1 consists of a control box and one transducer for $499. It was introduced in 2022 for smaller boats and can be used for drives, rudders, stabilizers and more. For $1,996, the HD4 comes with four transducers and a control box. Both systems can run off a house battery bank and have an available ECO Solar/Wind Power mode.
The company’s website answers many questions including how many transducers a boat would need depending on length. Each transducer provides about 200 square feet of protected underwater surface area. One transducer is required for boats shorter than 20 feet. Jump to 30 feet and the number of units doubles. Three transducers take care of hulls between 30 and 40 feet and four are needed for boats from 40 to 50 feet. You’ll need six broadcasters for boats from 50 to 65 feet. A cat up to 34 feet will need two transducers while a 50-footer needs four.
Hull Shield systems are used to protect drives and inboard shafts plus related equipment. A single transducer can protect a pod or sterndrive. An inboard engine or a sail drive would take two transducers, one for each propeller and rudder.
The HD system can work with 12- or 24-volt power systems and Hull Shield even offers a converter and battery protector. The company also makes available an indicator wire that can be run to the dash and connected to a light so a captain can see that the system is working.
Hull Shield has OEM relationships with Ocean Alexander, Boston Boatworks, Aquila, Grand Ocean and more. The company also offers the HDX system for larger vessels. It can be used for bottom protection and for onboard raw-water systems.
Mahaffey estimates that 70 percent of clients install the system themselves. The company has a dedicated customer support team and exhibits at larger boat shows in Florida and on the East Coast of the U.S.
Other companies offering ultrasonic antifouling include Ultra-SoniTec, which is the U.S. dealer for Clean-A-Hull, an Australian company. Ocean Navigator reached out to Ultra-SoniTec, but did not receive a response. Cathelco Limited Evac Group uses a sacrificial-anode-based technology and has built its business on preventing growth in internal raw-water systems on large ships. The group recently launched a system to prevent growth on hulls. n