With $240,809 in funding from the Washington State Department of Ecology, WSU researchers will test environmentally-friendly alternatives for antifouling boat paints.

Fouling is the formation of aquatic organisms on the hull of boats. It slows down the boat significantly and can cause corrosion to the surface, said Xianming Shi, Department of Civil and Environmental Engineering chair.

“The ship will have to consume more energy to be able to move at the original speed. It’s cumbersome. The surface was originally smooth, beautifully shaped, and now it’s growing all sorts of things … things like bacteria, algae, barnacles, sponges, tubeworms, all sorts of unusual stuff,” Shi said.

The U.S. Navy spends about $1 billion a year addressing fouling, he said.

Antifouling boat paints work by adding an antifouling coat to the top layer of the paint, he said. Copper-based paint is the most popular antifouling paint and was first used by the United Kingdom navy in the 18th century.

The copper leaches into the microorganisms and kills them with high efficiency, making the hull resistant to fouling, he said. However, it is also toxic to salmon and other important aquatic species.

Therefore, the state of Washington has sought to reevaluate and phase out copper-based paints since 2011, said Iris Deng, toxics researcher at the Washington State Department of Ecology.

However, without any data on the efficacy of alternatives, the state cannot ban copper antifouling paints, Shi said.

Deng said in 2019, Washington adopted California’s copper leach rate limit of 9.5 micrograms per square centimeter per day.

Now the legislature has directed the department to write a report on antifouling paint and alternatives, she said. The report will have multiple components, one of which is the performance testing carried out by WSU.

Performance testing of the different antifouling paints will be done according to the standards set by the American Society of Testing and Materials, Shi said.

These standards include what type of steel panels to test on and what primers to use, he said. The only variation between the panels is what antifouling paint is applied to them.

The panels will be secured in a rack and submerged in water. Every month, technicians visit each of the testing locations to measure the amount of fouling on each panel, he said.

His lab collaborated with Washington State Ferries, Port of Seattle and a private yacht club to secure four testing locations near the Puget Sound, he said. The four locations include Ana Cortes, Manchester, Point Defiance and Portage Bay.

These locations were chosen to represent different environments and ecosystems, he said. They were also chosen based on safety and accessibility.

“Some are on islands. We have to take a boat to the island. That would be too cumbersome. And some of them you have to basically be able to swim,” he said.

They will be testing twenty different antifouling paints. Some include copper, while others include alternatives, he said.

Alternatives to copper do not have to be biocidal, or toxic, Shi said. Some alternative antifouling paints are hydrophobic, meaning they repel water, which keeps aquatic species from sticking to the hull. When the boat speeds up, these species should simply fall off.

The data collected will be used to inform the Washington State Department of Ecology’s antifouling paint report to the legislature, Shi said.

However, if no suitable alternatives are found, it opens a window of opportunity for the researchers to develop their own antifouling paint, he said.

“The hope is that when we’re armed with such fundamental knowledge, we can probably help design, or even ourselves design, better antifouling paints, which are not only green but also effective,” he said.

Deng said the future of antifouling techniques will not only require better technology, but also involve good management practice, including cleaning.

She said the Department of Ecology communicates with industrial and recreational boaters to receive their input on antifouling paints.

“We are here to protect the environment of Washington state residents and create a healthy and safe and clean environment for the Washingtonians,” she said.