Welcome to the Finhouse

So Pete McCarthy was flipping through a magazine one afternoon a few years back and came upon a picture of the wind tunnel at the University of Colorado, Denver--the hollow fistula that engineers at the college send 100-mph winds through. Only a handful of people seeing that picture would think, “It’d be real neat to have a replica of that in my backyard.” But McCarthy, who had been looking for a way to build a wind tunnel, put away the magazine, took a sight line from the kitchen inside his apartment and built a wind tunnel right through the living room.

He added smoke-generating devices--everything a modern apartment dweller needs to visualize air flow--and for a time, McCarthy tested his airplane wing ideas next to the couch. After a while, the 32-year-old Newport Beach software salesman decided to quit his day job to devote his time to a new idea: reinventing the scuba fin. “Air and water are the same,” he says. “It’s just a matter of varying density. I could test fin design in the tunnel, visualizing air flow as water flow.”

McCarthy discovered that turbulence likes to curve around and gather atop the typical scuba fin when it is kicked; if it was an airplane wing, the jet would fall out of the sky. For divers, this means the scuba fin--the design has changed little in the past century--was actually inefficient. McCarthy redesigned the fin by splitting the blade in two. Upon seeing McCarthy’s fin--which is being manufactured in Japan, and which the inventor believes will make the standard fin obsolete in short time--one thinks, “Oh, he sliced it in half with scissors.” Actually, dozens of prototypes were sent through the wind tunnel. Those and about 300 others were sent by boat, out to Catalina Island’s Scuba Lab, where divers tested them undersea. Sometimes, he says, the new fin proved 25% to 40% more efficient than the standard.

When McCarthy describes his fin’s underwater efficiency, it can sound as fantastic as an “Eat what you want and still lose the weight!” diet: “Just let your legs literally relax,” he says. “That’s the kicking motion.” And for a moment, he seems like another huckster with a quick idea. Until the image of the wind tunnel, thrumming in his living room, sneaks back into your mind.