Message In a Bottle.(David de Rothschild in constructing a prototype for a sixty-foot bottle boat)

One morning last June, David de Rothschild, a thirty-year-old heir to the European banking fortune, arrived on his bicycle at Pier 31, a vast, hangarlike building that juts from the Embarcadero into San Francisco Bay, in the city's North Beach district. De Rothschild, who has a beard and shoulder-length brown hair, was wearing a flower-patterned shirt, low-slung corduroys, a belt with a skull-and-crossbones buckle, and flip-flops. He entered the building and pedalled toward a group of people at the far end of the space: a gray-haired man in a work apron who was cutting wood with a table saw and a younger man and woman who were hunched over a twenty-foot-long, bow-shaped plywood frame, which cradled, in neat rows, under a white nylon fishing net, thousands of clear-plastic water bottles.

For a month, the group had been constructing a prototype for a sixty-foot "bottle boat," which de Rothschild and a small crew plan to sail across the Pacific Ocean, from San Francisco to Sydney, Australia. A highlight of the trip, which de Rothschild hopes will begin in July and, if all goes well, end four months later, will be a visit to a huge region of floating plastic trash and particles, known as the Eastern Garbage Patch. De Rothschild will collect water samples to study and, using a satellite phone, post photographs and video clips on the Web site of Adventure Ecology, an environmental organization that he founded. His goal is to call attention to the perils of ocean pollution and to suggest a solution: waste as a resource. To this end, he had decided that his boat should be made entirely of recyclable plastics, produce its own energy, and generate no noxious emissions. De Rothschild has enlisted twenty-five people to help him realize his vision--consultants to design solar panels, wind turbines, and stationary bikes (to power batteries that would run small motors), along with a system to produce potable water from seawater and a "separating toilet," so that the crew's solid and liquid waste can be converted into fertilizer. The expedition is expected to cost several million dollars, much of which he has raised from corporate partners: the International Watch Company and Hewlett-Packard. Inspired, in part, by Thor Heyerdahl's Pacific crossing in 1947, on a raft called the Kon-Tiki, de Rothschild called his project Plastiki.

As a teen-ager, de Rothschild, who is six feet four, was a top-ranked horse jumper on Britain's Junior Eventing team, and he is an experienced bungee jumper and kite skier. He is also one of just a handful of people to have skied to both the North and South geographic Poles. (These feats earned him inclusion in the National Geographic Society's 2007 class of Emerging Explorers.) But Plastiki is of a different order of difficulty and danger from anything he has attempted before. Storms, sharks, isolation, injury, and illness are standard hazards for anyone attempting a Pacific crossing by sailboat, but de Rothschild is proposing to do it in an experimental craft made from materials that have never been tested against ocean waves. He plans to bring an electronic position-indicating radio beacon and radios that can provide up to forty-eight hours' advance warning of approaching cyclones. Even so, the boat, whose top speed is expected to be about ten knots, and whose steering system will allow only minimal maneuverability, may not be fast enough to dodge a Pacific cyclone, which can measure a thousand miles across.

De Rothschild, arriving at the far end of the pier, hopped off his bike--he does not own a car. (At his home, near London, he uses compact fluorescent light bulbs, buys his electricity from a green supplier, and maintains a colony of earthworms to consume his organic waste. Still, he commutes regularly between Europe and the United States, a habit that he acknowledges is less than ideal for an environmental activist. "My footprint is bigger than average but less than it could be," he says. "I try and take every action I can.") He asked Mike Rose, the man in the apron, how the construction of the Plastiki prototype was going. Rose, an Australian in his fifties who had been hired as the boat's builder, replied that he and his workers were having a "bugger of a time" trying to prevent the bottles from shifting under the nylon fishing net. Any movement, he said, could compromise the boat's shape.

De Rothschild bent down and poked at one of the bottles, which wiggled beneath his finger. The bottle itself, however, felt as hard as a brick, thanks to a technique that a member of de Rothschild's team had devised to enable the thin plastic to withstand the pummelling of the waves. Inside each bottle was some dry-ice powder, which had turned into gas and expanded, pressurizing the bottle. Rose's female worker, a Swedish college student, had spent three days with a couple of helpers putting dry ice into nearly six thousand bottles. (The actual boat will use about twelve thousand.)

"I was talking to Andy," Rose said, referring to Andy Dovell, the naval architect who is Plastiki's designer. "We were talking about the possibility of shrink-wrapping the hulls with Saran Wrap to hold the bottles still."

"It's a thought," de Rothschild said, without enthusiasm. "But then what's the use of having bottles? You could put anything under there."