No Barnacles Means Smooth Sailing

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Geoffrey Swain and His Research Team Keep Ship Hulls—and Our Environment—Clean

anti-fouling

At the end of Dock C at Cape Marina in Port Canaveral on Florida’s Atlantic coast, a huge Disney cruise ship looming in the distance, scientists and engineers were examining experiments just pulled from the seawater.

Attached to a series of secured frames were several panels—some covered in barnacles, sponges and mussels, others free of any sort of clinging creature or plant. The Static Immersion Test Platform, designed and fabricated by Florida Institute of Technology with funding from the Office of Naval Research, is dedicated to helping research methods to eliminate those hangers-on and their ilk from the hulls of Navy ships, a process called anti-fouling.

Leading the team is Professor Geoffrey Swain, one of the world’s most respected anti-fouling scientists. For 30 years, he and his researchers have made a global impact by improving the fuel efficiency and lessening the environmental impact of huge, ocean-going ships like the one moored across the water.

Applying anti-fouling coatings to a vessel makes it difficult for plant and animal life to stick to the the boat. Smooth, streamlined progress is key to a ship’s performance, and less resistance from barnacles and other marine life means better fuel economy and fewer greenhouse gasses. (World shipping is estimated to be the source of as much as 3 percent of total global carbon dioxide output.)

Moving Away from Toxic Chemicals

But anti-fouling is not that simple. Anti-fouling paints may contain biocides that are detrimental to the environment. One such biocide, tributyltin, or TBT, was extremely effective, but at a cost: it was found to adversely affect non-target organisms such as oysters and other marine life in waters near ports, shipping lanes and marinas.

Introduced in the 1960s, TBT is now banned worldwide. Scientists are now faced with the challenge of developing alternative methods to keep hulls clean and ships fuel-efficient without damaging marine life. Swain and his team help develop new formulations that function with reduced or no biocides, and they are also developing underwater robots to proactively groom and maintain surfaces free from fouling.

Swain has received more than $8 million in funding for this work, much of it from the Office of Naval Research. He also contracts with industry leaders such as Dow Corning Corp., DuPont Canada, General Electric, International Paint, Pittsburg Paint and Glass and Royal Caribbean Cruise Lines.

Anti-Fouling Draws Young Researchers

Recently, three members of Swain’s team became faculty members. With their new titles of research assistant professor, Kelli Hunsucker, Emily Ralston and John Hearin pursue anti-fouling science under Swain’s direction, but they also have the ability to apply for their own research grants. The research assistant professors are also key to implementing the research at the test sites. In one area of Cape Marina at Port Canaveral are the Static and Dynamic Test Facilities, where surfaces are evaluated for their ability to control fouling. The static immersion represents conditions a ship experiences when in port and the dynamic while the ship is at sea. The dynamic immersion is conducted from a rotating disk deployed off the stern of a catamaran simulating a boat cruising at 10 knots, all while secured to the dock.

“We are one of only a few test facilities in the world to have this capability,” Hunsucker said. “We are leaders in pushing this research forward and making others realize the importance of incorporating dynamic immersion into anti-fouling testing.”

Observing fouling on a moving vessel is important because the researchers have found that microscopic plants called diatoms prefer to grow on ships that are on the move more often than they are docked, such as cruise ships. These form layers of slime that can increase drag by up to 20 percent over a clean, smooth surface.

Hunsucker’s specialty is studying this plant life. The slime or biofilm is resistant to some of the newer coatings, so she is interested in looking at ways to prevent the buildup of these microscopic plants from attaching and creating costly drag penalties.

Ralston, who recently secured a grant to develop methods to prevent fouling on parts of boats that are not easily protected by coatings (such as propellers), studies settlement and recruitment of animals that attach to hulls, like barnacles and mussels.

“We want to protect surfaces that need to be protected, like boat hulls, but make it work with biology,” she said.

Ralston is interested in seeing parts of harbors and piers that don’t come into contact with boat surfaces be allowed to attract filter feeders such as bivalves to help purify the water. Copper, an effective biocide, can have its place, too, she said, but only if it’s managed well and balanced by healthy ports that attract organisms such as native oysters.

The in-water maintenance of coatings is also an important area of study, and it’s the specialty of John Hearin, an ocean engineer. He runs a Florida Tech test facility at Port Canaveral that is developing an autonomous underwater robot quipped with rotating brushes that gently and proactively maintain coatings in a smooth and fouling-free condition.

Recommending Best-Practices

Swain and his team run two other labs collectively known as the Center for Corrosion and Biofouling Control, at the Sebastian Inlet, and a testing facility on the Florida Tech campus in Melbourne. Between the three sites, Swain’s team is able to provide services to clients from all over the world, advising them on methods that help them prevent corrosion and control fouling.

Hunsucker says the team is dedicated to carrying anti-fouling science forward for a new generation of researchers at Florida Tech, with the end goal being environmentally friendly anti-fouling coatings.

“We are starting to see the marriage between silicon-based fouling-release coatings, similar to non-stick cookware in your kitchen, and underwater hull grooming. This would reduce the need for biocides, save on fuel and costs, and help ships reduce greenhouse gas emissions,” Hunsucker said.

“Our goal is to see these coatings and hull grooming become standard practice for both the Navy and industry.”

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