An unusual design process combining recklessness, imagination, and computers created one of the fastest-growing sports in history.

The promise of kiteboarding is that a wind strong enough to draw small whitecaps from the water can take you on a magic-carpet ride. But the same wind can be dangerously uncontrollable.Photograph from Alamy

Just as he was graduating from high school, in 1990, Chris Moore had a fanciful idea. He had noticed increasing numbers of so-called sport kites arcing through the skies above his home town of Lenexa, Kansas, outside Kansas City, Missouri. A traditional kite is tethered to its operator by a single line, and is more or less impossible to maneuver. But a sport kite—a needle-nosed, fighter-jet-like wing of nylon or polyester—has two lines, which an operator can use to induce acrobatic turns. Moore was skilled with a yo-yo and had watched riders do tricks on their bikes. He watched the sport kites soar, reverse, and double back, and wondered if the kite could become the next bicycle—a vehicle for art, competition, or some combination of the two.

After he graduated, Moore opened a kite store in partnership with his mother. Sales were slow. The problem, he felt, was that the kites he was buying from suppliers weren’t fast or trickable enough—they could only do a loop or two. Moore brought on an aerospace engineer from the University of Kansas named David Bui, and, together, they started reverse-engineering the kites. Bui turned out to be a gifted scavenger of parts. They built kites using the shafts of high-performance arrows, which were constructed of lightweight aluminum encased in a carbon-fibre wrapper; later, they made their own spars out of tapered graphite tubes that were being used in the production of helicopter frames. The technology they used was modelled on bird bones.

Moore, who has a compact build, a bright smile, and the serious, studious voice of an airline pilot, took his kites on the road, performing at schools and birthday parties, for Boy Scouts and Girl Scouts, and before crowds of thousands at kite expos. In the process, he became one of the most skilled kiters in the world. He and Bui made sixteen-square-foot sails that were stiff but weighed only three ounces. “I could literally walk and move, and my body created enough pressure against this highly controllable feather to orchestrate a whole routine to music,” Moore recalled. He was one of the first people to fly kites indoors—a boast, since it showed that the kites were so light that they didn’t even need wind. Moore had been right about the sport-kite business: he soon opened six stores in Missouri and Kansas, advertising in Stunt Kite Quarterly and other new publications devoted to the sport of kiting. Moore himself became one of its top professionals, travelling each weekend to tournaments around the country and earning a national title.

In 1994, Moore went to France as part of a seven-week European kiting tour. He watched as one of the other performers, with a paragliding sail at his back, made a controlled landing on the water, then used the sail to pull himself through the waves to shore.

“My mind was blown,” Moore said. “I was just connecting all kinds of dots.” He stopped his tour, tracked down the performer, horse-traded one of his kites for a glider, and took it back to the United States. In the past, Moore had been interested in making kites more maneuverable. Now he was fascinated by a different problem: harnessing their power to take flight himself.

In landlocked Missouri, he began a series of reckless experiments. He sat in a three-wheeled buggy, launched a large kite, and, by swooping it through the air, set himself racing across football and soccer fields. He strapped himself into a climbing harness, then tied himself to a soccer goal; by diving a kite down and up repeatedly, he was able to rise into the air, sometimes as high as sixty feet. He found that a well-timed flick of the wrist could bring him in for a soft landing. If his timing was off, he’d sometimes knock himself unconscious.

Moore didn’t know it, but similar experiments were happening all around the world. Wind speeds are higher at the altitudes where kites fly than they are at ground or sea level; in 1984, two French brothers, Bruno and Dominique Legaignoux, had envisioned a more efficient catamaran that was powered by a kite rather than a sail. In the course of developing their vessel, they had built and patented a kite with an inflatable leading edge, which allowed it to float when it crashed onto the water so that it could be relaunched. Their kite had made its way to Hawaii, where big-wave surfers were used to paddling out into swells or getting towed into breaks by Jet Skis. They began experimenting with wind power.

“I was living in my own world—I was in Missouri, in Kansas,” Moore said. There was no World Wide Web to bring these far-flung communities of enthusiasts together. Even so, through one of his customers, Moore heard a rumor. In Oregon, a Boeing engineer and his son, both avid windsurfers, had rigged their windsurfing sail to a long line, attached it to a pair of water skis, and then used the wind to pull themselves along the Hood River. Moore found out the names of the father and son—Bill and Cory Roeseler—and wrote them a letter. They replied with a VHS tape. “I put it in my VCR, and it was a video of this guy and his dad pulling themselves on this kite-like device,” he said. The Roeselers sold him one. When the contraption finally came, it affected Moore so deeply that he sold everything he owned, laid off more than sixty employees at the business he’d built, and moved east from Missouri to rebuild his life on the ocean.

In 1999, in Nags Head, North Carolina, Moore opened one of the world’s first kiteboarding schools. Kiteboarding promised to combine the best of wakeboarding, waterskiing, surfing, windsurfing, and paragliding; Moore’s school, Kitty Hawk Kites Kiteboarding, attracted hundreds of thrill-seekers willing to strap boards to their feet and kites to their waists. But the sport was a work in progress. There were no safety releases; if a kite, caught by a gust, went out of control, the kiteboarder went with it. “I really just scared the shit out of people,” Moore recalled. “Mostly, they quit after the first lesson.” There were stories of novice kiteboarders being flung into the sides of buildings; people broke ribs, or worse. The problem was obvious. The early adopters knew how to harness the wind—but they didn’t know how to tame it.

In the late nineteen-eighties, a few years before Moore discovered kiting, Don Montague started his own experiments in aerodynamics. Montague, one of the world’s best windsurfers, was frustrated by his performance in light winds. A windsurfer and his sail need to balance each other: only heavier riders can counterbalance the large sails necessary to draw power from low-speed winds. Montague weighed only a hundred and sixty pounds; in competitions, when the wind was low, he had to strap weights to his back. He longed for sails that were both lighter and more powerful, and decided to try to design them himself.

At first, Montague took a traditional approach. Sitting in the middle of a large sheet of mylar, he drew an outline of the sail he wanted in felt pen. He then placed battens—stiff strips of material, usually fibreglass—on the sheet, like ribs. By moving the battens, he could adjust the sail’s shape; by changing their length, he could alter the profile of tension it presented to the wind. And yet this process seemed, to him, alarmingly imprecise. Montague wanted to explore the space of design possibilities in a methodical way, and, from the floor, it was difficult to track changes from one design to the next. What he needed was software that let him move the battens virtually.

Montague is dyslexic. When he tried designing sails with standard “computer-aided design” tools, he found tweaking the numbers, which was the only way to alter a sail’s design in those programs, too irritating. Although he’d been a lifelong tinkerer—as a kid, he’d taken apart telephones and attached a sail to his skateboard—his only formal training as an engineer had been a drafting class at the University of California, Santa Barbara. (To save on tuition, he’d enrolled under the name of a Californian cousin; when a professor discovered the ruse—his daughter, Montague recalls, turned out to be dating the cousin—his time at the university was cut short.) Montague decided that he needed software that would let him play directly with sail designs, and recruited a small group of programmers who worked out of a garage in Maui to build it. “Because I was very visual,” he said, “the programs needed to be extremely visual”—fewer numbers, more pictures; fewer formulas, more drawing tools. The programmers made software that showed him a sail’s shape in three dimensions, allowing him to change the parameters he cared about with a few clicks. It insured that all the parts of the sail would fit together and created a blueprint for the final product.

Later, Montague tried to build software that could simulate a sail’s real-world behavior—accounting for the weight of its mylar, the motion of its boom, the choppiness of the waves. But simulations, he found, were less useful than experience on the water, and so he tested his sails by surfing with them. His tests were driven primarily by feel. Was the sail breathing enough? Was it too stiff? “Point five of a millimetre in takeup on the leech of a sail”—the back edge—“is the difference between a good sail and a bad sail,” he said. “Within ten seconds, I would know what was wrong.” A sail, he concluded, is “basically a living membrane. And unless you approach it like that—if you’re just looking at the numbers . . . you get nothing.” He went on, “You know, we are a computer. . . . So you can’t really say, ‘Oh, you need this fancy computer program.’ I’m actually the best computer you could find for this application.”

By the early nineties, Montague had perfected his more powerful windsurfing sails. His designs—which he refined as the head sail designer at Gaastra Sails and, later, the head of R. & D. at an outfit started by Robby Naish, a legendary surfer—sold in the hundreds of thousands, and transformed windsurfing. (Eventually, Montague would start Makani Power, a wind-based electricity company, which Michael Specter wrote about for The New Yorker, in 2013.)

Like Moore, Montague heard rumors about the Roeselers and their kite ski; in 1993, he met Cory, the younger Roeseler, in Maui. They talked about turning kite-skiing into a sport of its own. But Montague was skeptical: the wind was just too strong. “He was a super-fit guy,” Montague recalled, of Cory Roeseler. “He had gigantic legs to hold these skis in the water.” It took great strength to control the heavy bar of Roeseler’s carbon-fibre-framed kite, which, Montague said, could “whack you in the face.” Kite-skiing seemed more like a stunt than a sport. “ ‘People are going to get hurt,’ ” Montague remembers telling Cory. “ ‘It’s just not going to work. Even though you can do it, no one else can. You’re superhuman.’ ”

I first experienced the power that both Moore and Montague were confronting a few years ago, on an overcast day in Providenciales, in Turks and Caicos. The promise of kiteboarding is that a wind strong enough to draw small whitecaps from the water can take you on a magic-carpet ride. But the same wind can be dangerously uncontrollable.

New kiteboarders start on land, by learning to fly a small “trainer” kite. Mine was powerful enough to drag me up onto my toes. My instructor drew a small semicircle on the beach: the “wind window.” When the kite sits at the top of the window, or to the sides, it’s in neutral; when it swoops inside the arc, it enters the “power zone.” If you swoop too aggressively and lose control of the kite, it can start spinning. In a “death loop,” the spins become unstoppable; the kite gathers speed, pulling you along with it.

After an hour or so, my instructor hooked the trainer kite’s big brother—a bow kite with a fifteen-foot leading edge—to a harness wrapped just below my rib cage. I had been warned about its power; now I was tethered to it. Feeling its pull, I was reminded of riding a horse: each of the kite’s small motions suggested irresistible strength, and pretending to control it was hubris. Whenever I lost focus, the kite swooped and pulled me downwind. I watched the lines: if my fingers got caught in them, the kite could rip them off.

My first time out, I flew the kite too timidly and barely stood up. Later, at the instructor’s urging, I flew it too aggressively and face-planted in saltwater. In kiteboarding, the learning curve is unusually steep: a rider must coördinate kite and board while reacting to the changing wind. For two weeks, I was often scared and uncomfortable. Then, my first real ride: I coasted for half a mile toward open sea, bright blue above and below, the sun hot, my skin wet, the wind high and warm. I shouted to myself in disbelief. Speed is freedom and freedom speed; that is all ye know on earth, and all ye need to know.

In the mid-nineties, when Montague tried his first kiteboarding setup, the problem of “de-powering” was foremost in his mind. “When I got hold of it, it was, like, ‘We can’t use this in Maui,’ ” he recalled. “ ‘It’s twenty-five knots here—we’ll die.’ ” On a boat, it’s possible to let the wind out of a sail by tightening a line. Kites had no such ability; in fact, in a crash, they tended to fall directly into the power zone, with the strongest wind. “The only reason we all didn’t die in the beginning is because we were already watermen,” Montague said.

While working on their kite-powered catamaran, the Legaignoux brothers had nearly solved the de-powering problem. They could never quite perfect their approach, Montague says, in part because their prototyping process was so slow: they developed their kites by cutting full-scale models out of foam blocks. Montague had the advantage of his sail-design software. He began laying out designs on the computer and bringing them to life outside. “I was so crazed about it that I would be flying the kite in a field at night, in the dark, without looking at it, so that the kite was now an extension of my body,” he said. “Just like windsurfing, it was an immediate feeling.” Montague sewed webbings to the bottom of his kites and attached the lines in combination until he got the behavior he wanted. He brought a staple gun to the beach, so that he could change a kite’s shape with a few staccato snaps.

Montague’s kites had all the power of the old models, but only when you wanted them to. They were dynamically stable, like airplane wings, with a natural tendency to park high and soft, exerting comparatively little force until it was summoned. In a crash, they flapped harmlessly instead of gathering speed. Early kiteboarders had ended their days miles downwind from where they’d started, shuttling themselves back to their launch points by car; Montague’s new kites could go left, right, upwind, or downwind. “The day I stayed upwind in Ho’okipa,” he said, “That was the day the sport was real.”

What followed was a kind of Cambrian explosion—a cascade of small breakthroughs. “Every year was some new mind-blowing thing,” Chris Moore recalled, of the early two-thousands. As the equipment got better, students became more likely to stick around; their demand, in turn, drew more investment in equipment. “Suddenly, the sport became way safer,” Moore said.

A technical revolution can take root only if there’s a human infrastructure behind it. “I started teaching people how to teach,” Moore said. He trained thousands of kiteboarding instructors and developed and conducted instructor examinations. He learned that teachers of high-risk sports have huge liability exposure—a hang-gliding school, for example, might only obtain insurance after proving that it rigorously trained its teachers—and created the Professional Air Sports Association, which began certifying kiteboarding instructors so that the schools could get insured.

Kiteboarding began developing the social on-ramps—culture, community, distinctive rituals and vocabulary—that could turn it from a dangerous hobby into a sport. Today, more than a million and a half people participate. Kites litter beaches in Brazil, Egypt, and South Africa; in the Caribbean and in San Francisco Bay, they sometimes crowd to the point of colliding. As with horseback riding, standardization of the equipment and teaching allows newcomers to forget the improbability of what they are actually doing. A sense of inevitability descends. Of course we sit on the backs of two-thousand-pound animals and order them around; of course we strap ourselves to wakeboards and kites in fifteen-knot winds.

This summer, I rented a kite—a fourteen-metre Cabrinha model, the descendant of a descendant of a design by Don Montague—from Chris Moore’s school, which is now located in Turks and Caicos, and went to the beach. After fifty hours of practice, it was time for my first unsupervised kiteboarding session. I unzipped the oversized backpack and unfurled the fabric downwind; it flapped gently until I pumped it to life. I flicked the inflated leading edge and listened to the pitch; a high note signalled good pressure. Earlier, I’d watched a well-produced YouTube video with animated overlays that reminded me exactly how I should connect my lines. The control bar to which the lines attached was color-coded, and I used a mnemonic, “red rigs right,” to remember which side went where. I clasped my safety leash to the bar and then hooked it to my harness using the “chicken loop,” a device that would allow me to disable the kite in case I lost control.

It’s customary for a kiteboarder to launch with the help of a partner. As I walked sideways into the water, a stranger on the beach righted the kite. It waited, parked in neutral, while he held its leading edge; I gave the signal to launch, and the stranger let go. Most kiteboarders stick to the surface, where they can do everything that windsurfers can, but with far less wind and muscle; the default pose is to recline, shoulders back, hips forward to carve. But it’s easy to take flight. If the wind is good, a light pull on the control bar will start the bow-shaped kite on a turn toward its apex, into the full force of the wind. At the right moment, you turn the board hard upwind and pull the bar: a surge of power lifts you skyward. A beginner might hop a foot above the water, abs tight with effort, then lose the board and crash. But the best riders can rise dozens of feet in the air, then ride away after a soft landing.

I looked around. The waves were short and smooth, the water bath-warm and indigo; for more than a mile, it was no deeper than my waist. The bay seemed designed for kiteboarding. With a few swoops of the kite, I got myself up and moving. It felt entirely natural when I leaned back and cut upwind.

The The New Yorker