A research team from the Zoological Institute of Kiel University in Germany developed a silicone coating which they say reduces the contact area of barnacles to ship hulls by more than 50%.

In early tests on yachts, the researchers say that no barnacles or other "macro-foulers" could remain attached to the test coatings.

Microscopic electron image of the micro-structured silicone surface. Source: Lars HeepeThe research offers a new understanding of the wetting behavior of biological adhesives in the marine environment. Study results were published in the Journal of The Royal Society Interface.

The researchers say that adhesion plays an important role in nature. Barnacles and mussels use complex adhesives to permanently attach themselves to natural and man-made surfaces, such as ship hulls or offshore facilities. Organisms can damage these surfaces and, in the case of ships, increase fuel consumption through greater flow resistance. Conventional methods to protect ship hulls against unwanted bio-fouling often involve environmentally harmful toxins.

The researchers first analyzed the wettability of barnacle cement, meaning the ability of the organisms to adhere to surfaces underwater and to spread their adhesive across the surface.

"Our research has shown that adhesives used by organisms that settle underwater can stick to almost any surface," says first author Dennis Petersen. The reason is the complex chemical composition of these adhesives.

With that insight, the researchers developed a coating made of a non-toxic silicone with a new microstructure. Similar to the lotus effect that causes liquids to roll off smooth surfaces, the new structure's geometry prevents a strong adhesive bond between barnacles or mussels and the coating surface.

In a first practical test, parts of the hull of four sailboats of the Kiel Yacht Club were covered with the new material and tested for one season. The tests showed that no barnacles or other macro-foulers, such as mussels, could be found on the coating. The material also enables barnacles on hard materials to be detached without leaving any residue.