This is a fascinating article.

According to the Navy, algae and barnacles on hulls increase drag,
slowing ships and reducing fuel efficiency. Of the $550 million to $600
million the Navy spends annually on powering its ships and submarines,
at least $50 million stems directly from fouling-related increased
drag....
Sharks have placoid scales, which consist of a rectangular base
embedded in the skin with tiny spines or bristles that poke up from the
surface - the reason a shark's skin feels rough to the touch.
Brennan decided to try mimicking that surface with an artificial
coating to see if it would also have antifouling properties.

His first product: a combination plastic/rubber coating that a
microscope reveals is made of billions of tiny raised diamond-shaped
patterns. Each "sharklet" diamond measures 15 microns, or 15
thousandths of a millimeter, and contains seven raised ribs that at
close examination resemble different lengths of raised horizontal bars.
Laboratory tests show that the coating prevents a very common and
detrimental type of algae, called Ulva, from becoming established
because the algae's spores have great difficulty attaching to the
diamond-shaped configuration.

Entire article can be read he
http://www.sciencedaily.com/releases...0310180225.htm