Technology Review, June 8, 2001

The Great Sub Race

So what exactly is the point of a human-powered submarine?

By Eric Bender

If you are easily distracted, this is one vehicle you don't want to drive.

You are floating ten feet under in a dim vast tank that is lit from below by a few bright runway lights and lined by Navy divers ready to rescue you. The sub is so narrow that you did not get in it so much as put it on. You are lying down, with your hands on the controls that "fly" the sub and your feet on the pedals that drive its propeller. You are ready to kick off a furious 15-second explosion of energy that would intimidate most trained cyclists and will leave you gasping for breath.

Oh, and did we mention that the sub is open to the water, so you're breathing via scuba?

This is the high-tech, higher-effort world of human-powered submarine racing. And it will draw 19 crews to a U.S. Navy research facility outside Washington, DC this weekend.

And Sub It Goes

The first International Sub Race, open to one- or two-person "wet" human-powered subs, took place in 1989 in the waters off Riviera Beach, FL. Held every other year, the event gathered 44 contestants to Fort Lauderdale in 1993 when a storm blew in and started making logistics very, very expensive.

"The manpower and resources required to be on the ocean are immense," explains race organizer Nancy Hussey, director of the Foundation for Underwater Research and Education in Williamsburg, VA. "We couldn't afford the huge cadre of boats,

jetskis, divers and people on the beach."

Fortunately, for the next round in 1995 the Navy offered up its giant test basin at the Naval Surface Warfare Center in Bethesda, MD, which has hosted the event ever since. Speed trials are run for 10 and 100 meters in the narrow three-kilometer-long tank, with a rigorous adherence to safety procedures in which those Navy divers are the last resort.

Most entries at the all-volunteer event are from college engineering teams. Each sub is built from scratch. The subs show slick hull designs, esoteric materials, cleverly customized propulsion systems and other innovative thinking. But their payoff is not commercial spinoffs but the hands-on experience students get in building and running underwater craft.

The payoff for the Navy and the race's commercial sponsors is similarly straightforward: "These are the cream of U.S. students who will be next year's employees," says Dan Dozier, Navy liaison for the event.

Blood, Sweat and Teardrops

In the last underwater war in 1997, the University of Quebec's one-person OMER 3 was champion. It hit a record speed of just under 13 kilometers an hour (about seven nautical miles per hour)-almost twice as fast as Olympic freestyle swimmers.

The OMER team will defend the title with OMER 4, a state-of-the-art one-person craft built out of carbon fiber and other esoteric materials. The smooth 3.7-meter hull is shaped like a long narrow teardrop and should offer less drag than its predecessor, says Simon Joncas, who led the 1997 team and is now faculty advisor. OMER 4's high-aspect propeller automatically changes its pitch (angle of attack) as speed increases, tweaked by a small battery.

OMER doesn't slack on the human element either. Its 15-member crew includes a champion cyclist as lead pilot, and a cook. (There are no nearby restaurants, Joncas explains, and a steady supply of good food keeps everyone well-fueled-especially crucial for the all-critical time in the tank.)

At the other end of the scale, Scuba-Doo is the vision of one high-school student, Logan Rainard, and his mentor Ed Leibolt, a Navy engineer. "Since January, I have been spending every spare minute of my life working on the sub, and Logan's been spending more," Leibolt says. "Our budget was non-existent-everything was done in the garage or the back of my pickup truck." But Scuba-Doo has already run speed trials in the giant tank and done quite well.

Tune Up That Tuna

While propeller-driven subs rule in speed, the race also encourages non-propeller entries.

This year, for example, the Merchant Marine Academy plans to bring a sub that mimics the swimming behavior of a bluefin tuna. Two-thirds of the craft acts as a tail, with cables pulling the tail into an arc.

"We've had a couple of other flappers, but they haven't worked too well," comments race director Jerry Rovner. "One team even tried jet propulsion," shooting water behind it.

This Reality Ain't Virtual

Race veterans speak wistfully of returning to the sea, perhaps with a smaller group of subs that do well in the tank, if they can find sponsorship.

But for now, many of the subs get plenty of real-world experience while suffering through their early shakedowns in lakes.

The race itself provides plenty of challenge even in the highly controlled test basin. With crews madly flailing away, it's not uncommon for subs to roll, plunge wildly up or down, or crash into the side of the tank. "If we hit a wall, it's all over," says OMER's Joncas.

For some students, the race brings a sea change. "Kids often say, 'I've learned more in a week of racing than I've learned in the classroom in the past four years,'" says Rovner.

Eric Bender is editor of technologyreview.com.