What's new at the pool: A new design for fins
The last big innovation in swimming fins - those rubber appendages that give scuba divers and snorkelers more leg power - came in 1965, with the introduction of vents. The vents, by allowing water to pass through the fin, reduced drag and made, kicking less laborious.

Pete McCarthy, a 32-year-old scuba-diving entrepreneur, had not even been born when the vented fins first appeared. But Mr. McCarthy has just patented a type of fin that he says will require a lot less exertion on the part of divers.

In anthropomorphic terms, Mr. McCarthy's fin more resembles the tail of a tuna than the webbed foot of a duck. "It's split into two slender wings that are kind of V-shaped," Mr. McCarthy said. "It acts like a fish tail."

The fins rotate somewhat like the propeller blades on a boat, he said. "Only they don't go all the way around."

Mr. McCarthy - who said he came up with the design through trial and error after experimenting with about 200 handmade prototypes - quit his job as a software salesman in 1996 to work full time on his idea.

The fins allow a diver to go faster than he would wearing conventional fins, Mr. McCarthy contends. Using an underwater speedometer that he also invented, Mr. McCarthy said he had clocked divers going about 30 percent faster with his fins.

But that is a bit like claiming that a new car can go 150 miles an hour. Impressive, but not particularly relevant if it is used for commuting and running errands.

A more meaningful measurement, said John Hardy, who runs a scuba products testing company called Scuba Lab on Catalina Island, California, is the consumption of oxygen.

Mr. Hardy, whom Mr. McCarthy paid to test his fins, said the split fins did reduce divers' air consumption. "The fins are from 20 to 40 percent more efficient than conventional fins," Mr. Hardy said. Mr. McCarthy said divers wearing his fins just perform a small flutter kick, rather than the big bent-knee kick that is most effective with traditional fins. "No knees at all," he said. "You just roll your ankles."

Apollo Sports, a Japanese company that distributes diving equipment in the United States, has licensed Mr. McCarthy's patent and will be coming out with its version of the split fin this summer.

Mr. McCarthy, who has a company called Nature's Wing, in Newport Beach, California, said he had also licensed patent 5,746,631 to other companies that will be developing their own versions of the fin.

Patents are available by number for $3 from the Patent and Trademark Office, Washington D.C. 20231.