The fouling of ships’ hulls, whether by barnacles and seaweed or by slime-creating bacteria, is a major problem for shipping worldwide, and particularly for navies. It has been estimated, for example, that fouling of hulls can create such turbulence as a ship moves through the water that fuel consumption is increased by as much as 30 percent. Traditionally major users of ships, like the U.S. Navy, have attempted to resist fouling by painting hulls with paints containing copper or triorganotin, a tin-based compound. But these paints are highly toxic and can leach into the water, killing marine life. That’s why their use increasingly is being prohibited. But help is at hand: A research group at Cornell University, Ithaca, N.Y., led by Christopher Ober, has developed two types of non-toxic paint, one hydrophilic and one hydrophobic, that effectively prevent fouling, whether by bacteria or barnacles. The paints act not only by minimizing adhesion by organisms but also by enabling hulls to become self-cleaning: As a ship moves through the water at 10 to 15 knots, the turbulence created removes the clinging barnacle or seaweed.
“They’re very good at what they do, says the U.S. Navy’s Paul Armistead. Powerful even. They work fast, possess a tenacity that is remarkable, make it look easy, and they’ve been at it since the beginning of time. What’s more, they do it underwater. Billions of them glue themselves to ship hulls and cost the U.S. Navy over $50 million a year in fuel costs alone due to friction and drag. What’s worse is that each of the Navy’s ships is obliged to be cleaned in port yearly ? sometimes even more frequently. We’re talking the humble barnacle. Historically, everything from pitch to pesticides has been used to try to deter it, but nothing seems to repel completely this lowly, but determined crusty fouler. Now consider the sleek, smooth dolphin, which can spend its entire life in the water and never host a single barnacle, while a ship ? also designed with a smooth, sleek hull ? can develop a bad case of them in less than a month….