When Paul Larsen Decided to Sail Faster Than Physics Would Allow, He Had Only One Choice: Reinvent the Boat

When Paul Larsen decided to sail faster than physics would allow, he had only one choice: Reinvent the boat. non-commissioned tk credits rocket1 WIRED MTK 2012 illustration by first lastname photograph by first lastname rocket

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non-commissioned credits tk illustration by first lastname photograph by first lastname Photographs b By Ad am FISHER y Jona than T orgovnik ship MTK 2012 WIRED 2

Speed boat SailRocket may be a boat, but it has the DNA of a plane. At the core of the design is a unique trait: Unlike other sailboats, this speedster never leans. As a result, every ounce of wind is translated into forward motion. This power play is mated with equally impressive tricks to minimize drag—be it from air, water, or the perplexing cavitation effect (see “Breaking the 50-Knot Barrier,” page 89). —A.F.

Fuselage Tapered like a dragster to reduce wind resistance.

Seen from across Walvis Bay, the windswept Spatch of Atlantic Ocean known as Speed Spot is barely more than a sparkle of white- caps against a long, low sandbar. As we get closer to what is one of the world’s most perfect speed-sailing areas, I scan the shore. It’s featureless save for two small shelters. We motor our zodiac inflatable toward the remote beach until we have to kill the outboard and tilt it up to spare the prop. The five of us jump overboard into the waist-deep water, following our guide, Paul Larsen, who is wading toward the shore. The wind howls in our faces, blowing so much sand that it runs down the beach in rivulets, like rain across a windshield. We Foil (aka keel) climb up on the beach, jellyfish at our feet Tilted at a 30-degree angle like as thick as paving stones. “This is it. This the sail, it keeps the boat from is the Bonneville Salt Flats of speed sail- flipping (or taking flight).

ing!” Larsen shouts, gesturing to the water G etty I mages by R e p ortage

092 WIRED feb 2013 wing (aka sail) A carbon-fiber sail tipped at a 30-degree angle to generate maximum lift.

beam Positioning the wing and foil away from the hull and on opposite sides prevents the boat from leaning—all power goes into forward motion.

pods Designed to minimize contact with the water. just off the sandbar. The fly- Paul Larsen ing sand sticks to our teeth, (center) and his team celebrate turning the insides of our a successful run mouths to 600-grit with at Speed Spot every word. “We’ll have to in Walvis Bay, Namibia. shovel out the timing hut,” Larsen says, peering into the primitive shelter he built years ago and pointing out animal tracks inside. “Jackal,” he concludes. There is a shipping port on the far side of the bay, but over here the landscape is so desolate, so extreme, that we could be on an alien planet—Frank Herbert’s Arra- kis, George Lucas’ Tatooine. In fact, we are in Namibia, a Texas-sized country at the southwest corner of the African continent. Walvis Bay is one of the Atlantic’s great natural harbors, but it’s surrounded by emp- tiness: 31,000 square miles of desert. The dunes march right into the sea, setting up an elemental cycle that repeats itself nearly every day of the antipodal summer. Morn- ings break as clear and sunny as a Baywatch shoot, but in the afternoon, near-gale-force winds descend on the bay. The desert heat meeting the cool Benguela Current coming up from the Cape of Good Hope creates a powerful natural wind machine. It arrives

every afternoon, steady and relentless. an airplane hangar than in any harbor—a and even something like landing gear— “No ruffles,” Larsen says, feeling the wind futuristic craft that, if he can make it work, three pod-shaped floats that keep the with his hand. The featureless landscape— will not only capture the outright world wing and fuselage above the chop. Yet no vegetation, no terrain, no fences, no speed-sailing record but also open up a what looks at first glance like a water- buildings apart from the shelters—makes new, no-limit era in sailing. “A hundred striding sailplane is, on closer inspection, for perfectly organized air. “Attached knots, maybe?” Larsen speculates from pure crazytown. For one thing, her wing is flow,” he calls it, using the jargon of an inside one of the huts, looking through a inclined at a 30-degree angle to the water aerodynamicist evaluating a successful sandblasted window at the watery speed- and is nowhere near the fuselage. Instead, wind-tunnel test. sailing course just beyond the beach. The it’s mounted on the end of a 30-foot-long Larsen is originally from Australia, but current record is just over 50. beam. The pole is, in a sense, an odd sort he searched the world for years to find this Floating behind the zodiac is the boat of mast—except that it runs horizontally. spot, a perfect natural runway to test a sail- that has brought Larsen to Speed Spot for On the opposite side of the boat is a blade- boat so radical that it is more at home in the tenth time in as many years in pur- like carbon-fiber fin. Technically this is

suit of sailing’s speed record: the Vestas the keel, or as Larsen calls it, the foil. Sail l id arve SailRocket Mark 2. Its aeronautical DNA is Rocket’s foil sprouts from the side of her Adam fisher ([email protected]) obvious at a glance. There’s a rigid carbon- fuselage, then turns to cut 3 feet down into wrote about the high tech scheme to fiber “wing” that functions as a sail, an the water. Critical to any sailboat, a keel

televise the America’s Cup in issue 20.08. ultra-streamlined 40-foot-long “fuselage,” keeps a boat from blowing over—or, in this He l ena D courtesy

094 WIRED feb 2013 breaking the 50-knot barrier The reason you can’t break 50: cavitation, a phenomenon that creates tremendous drag. The solution: a radical new keel design.

cross section of a standard keel

A standard keel is contoured like a But around 50 knots, cavitation kicks in: teardrop. This is an extremely efficient Pressure on the trailing edge plummets, design (even fish take this shape); making the water boil. The bubbles water flows around the keel smoothly. create drag, which halts acceleration.

cross section of sailrocket's keel

case, from flying away. “She’s 50 percent plane, 50 percent boat,” Larsen explains. Indeed, if Sail Rocket were dropped from a great height, it would glide down rather than fall. Larsen designed in aerodynamic stability as a safety measure. “If for some reason she lost the keel at speed,” Larsen explains, “than she really would be a plane, wouldn’t she?” The prototype version of SailRocket, Mark 1, actually did take off into the air, and Larsen survived what may be the most spectacular crash in sailing history. Paul Larsen’s new hydrofoil keel is a But once the boat gets up to speed, It was 2008 and he was at Speed wedge. At low speed it leaves messy an air pocket forms behind the foil, eddies in its wake, producing more re-creating the classic teardrop shape. Spot putting the Mark 1 through its drag than a standard keel and mak- Because the back “edges” are just air, paces when a gust got under the boat ing it hard to get started. cavitation bubbles can’t form. and launched it clear into the sky. The half-plane/half-boat hit an altitude of

illustration by brown bird design between 40 and 50 feet while cartwheel- bles attacking a boat’s keel will stop it ing through a flip—before crash-landing from accelerating, in the same way that upside down and backward. “It just kept the piling up of sound waves can halt a going up and up,” Larsen said at the time, plane’s acceleration. The hydrodynamics “then it hit bloody hard on my head.” of the 50-knot barrier and the aero Larsen is confident enough about the dynamics of the sound barrier are anal- stability of his revised design, the Mark 2, that he included a passenger cockpit behind the driver’s seat. It’s never seen a passenger, however. “I haven’t AS I CLAMBER ABOARD installed the seat yet,” Larsen says, “but I’m going to have to SAILROCKET, I FEEL test it out sooner or later …” He cocks an eyebrow in my direction. “Would that be good for LIKE SLIM PICKENS your story?” ASTRIDE THE H-BOMB In 1947, Chuck Yeager strapped himself into the experimen- IN DR.STRANGELO VE tal Bell X-1 “bullet with wings” and broke the sound barrier 8 miles above the Mojave Des- ert in Southern California. Larsen sees ogous—they’re both limits imposed by himself as following squarely in Yea- the physics of their respective mediums. ger’s footsteps. To become the fastest Yeager pierced the sound barrier with sailor in the world, he’s going to have to brute force. He had a rocket engine. break through the nautical equivalent of Under the right conditions, the brute the sound barrier—the so-called 50-knot force method can also get one through barrier (about 57 miles per hour). The the 50-knot barrier. This is not just theory. name is something of a misnomer, because The Russians proved it with their super- the barrier can drift slightly higher or cavitating torpedo, the Squall. Darpa has lower depending on things like salin- doled out millions of dollars in R&D con- ity and water temperature. But it doesn’t tracts for the Navy’s Underwater Express move too much, and when it kicks in, program, which aims to build a super “it’s like driving your car into a wall,” cavitating submarine. Supercavitating Larsen says. bullets shot from underwater rifles have That wall is caused by a phenomenon, even cracked the speed of sound. But a still not fully understood, called cavita- sailboat that can top 50 knots? It’s absurd. tion. It’s familiar to every powerboater There is no such thing. right, he not only takes the speed record who has ever over-revved a propeller. At a Granted, some powerboats do cruise for sailing, he also opens the door to an certain point the prop will begin to “cavi- at higher speeds, but they’re simply entirely new class of travel. “Just like with tate,” the water around it literally starting sidestepping the cavitation problem. the sound barrier, once you’re through, to vaporize. There’s a classic high school Speedboats, unlike sailboats, don’t have you’re through,” he says, “and the equa- physics experiment where you put a glass keels—they skip over the water instead of tion for doing 100 knots or greater will of water under a bell jar and then pump plowing through it. Most vessels, however, have been written.” out the air. Eventually the water bursts need some sort of keel in the water to stay into a boil. The physics are similar with upright, and sailboats need a keel to move. Back at Speed Spot, Larsen has just offered me cavitation: The pressure drops at the trail- That keel functions as a hydrofoil, resist- a chance to ride shotgun on SailRocket’s ing edge of a spinning propeller, and the ing the lateral pressure of wind on sail and test run, and I don’t have to be asked twice. water around it boils. When a prop cavi- translating it into forward motion. Yeager I grab a GoPro camera and wade over to the tates, it stops generating thrust and starts made it through the sound barrier with boat. There is no ladder and no deck; the generating bubbles. a rocket-powered battering ram. Larsen body of the boat is a long, low missile held Boats rarely move through the water is trying to make a similar breakthrough a few feet above the water’s surface by its as fast as a spinning propeller does, but using sail power alone. three floats. Getting to the cockpit is a chal- when they do, they also cavitate. The With a radical new keel shape, Larsen lenge. It’s a matter of clambering up onto enormous amount of drag created by bub- thinks he has cracked cavitation. If he’s the front float, swinging a leg over the nose

096 WIRED feb 2013 AS I CLAMBER ABOARD SAILROCKET, I FEEL LIKE SLIM PICKENS ASTRIDE THE H-BOMB IN DR.STRANGELO VE

SailRocket is likely the only sailboat in the world with a five-point seat belt cone, and then using both hands to scooch (the keel), lowering it to its harness. From the as well be driving a top- down the fuselage, a couple of inches at a go. proper depth in the water. cockpit, the pilot fuel dragster. He looks out can’t see the wing or SailRocket is painted orange in The Ethernet cable sends the rudder. over the nose cone, which homage to Chuck Yeager’s Bell X1, information back: the angle is angled slightly down like but as I inch along, it’s Slim Pick- of the wing, the angle of the that of the Concorde jet, ens astride the H-bomb in Dr. Strange rudder. Larsen’s cockpit is the better to keep the boat love that comes to mind. Eventually I wired with digital readouts, glued to the water. I posi- reach the auxiliary cockpit and climb since he can’t actually see either the wing tion myself facing aft like a tail gunner so I inside. I’m in a coffin-sized carbon- or the rudder from where he sits up front. can see how the boat works. The wing is on fiber tube, with control rope and Ethernet My cockpit has the GPS unit, which will the port side of the boat (my right, Larsen’s cables running through the inside. It’s a track our speed. left), and the foil is to starboard. Larsen tangle—half rigging, half wiring—but most Larsen straps himself in. SailRocket is and I are back-to-back. “The main thing,” of it eventually makes its way from Lars- probably the only sailboat in the world he says over his shoulder, “is to stay clear en’s cockpit past me and then down into that comes with a five-point seatbelt har- of the ropes.” the blackness of the tapering fuselage. The ness as standard equipment. He’s angled As Larsen mentioned, there is no seat ropes control most of the boat’s moving low, hands on a tiny steering wheel nearly installed in my cockpit (much less a five- parts. They maneuver the wing in and out between his knees, his helmet just peek- point harness), so I’m on my knees, being and engage the hinge of the scythe-like foil ing over the edge of the cockpit. He might careful not to touch any of the lines.

feb 2013 WIRED 097 They’re almost vibrating with tension, a position by the team on the zodiac, Larsen namic streamlining—is optimized for clear hazard. The cabling I’m not so wor- gives me the preflight briefing. The wind high speed, the real challenge to sailing it ried about, because a gremlin has already is blowing at 30 knots or so, which is ideal. is getting the boat started. Moving the rud- gotten into the wiring harness and Lar However, my extra weight means that it der doesn’t have much effect at low speed, sen’s wing and rudder readouts are on the may be hard to get SailRocket’s front float yet to accelerate you need to get the boat fritz. He’ll be piloting this run blind, sail- to “plane”: That’s the point where buoy- pointed in the right direction. ing by feel alone. As I crouch down, I con- ancy is replaced by hydrodynamic lift and “I’m at full lock with the steering,” sider what would happen if we ended up SailRocket’s floats stop bobbing in the Larsen says after a frustrating minute or in one of the catastrophic crashes that water and start to skim across it. So there so. “There’s just too much drag to let the plagued Mark 1. From where I sit, a high- are no guarantees. But with a thumbs-up, nose come around.” In other words, there’s speed bailout seems like a really bad idea. Larsen signals to the zodiac to let us go, too much cargo for this bird to fly. We’ve Hitting the wing beam to port would obvi- and he starts the launch procedure. drifted nearly halfway down the course in ously break every bone in “The wing is fully stalled,” a dud start. I’m wondering about lunch. my body, while the foil on Larsen reports. “We’re But Larsen says, “Let’s try it again.” the other side looks like it Paul Larsen and being pulled along like a could slice me in half. team TK Helena square rigger.” Since every Paul Larsen designed and built SailRocket with Darvelid pull While SailRocket is being SailRocket into element of SailRocket—the little more than a high school education. He dragged upwind and into Walvis Bay for one wing, the foil, the aerody- was raised in the rural northeast corner of more shot at the speed-sailing record.

098 WIRED feb 2013 Australia. “We were thick in the bush—30 out at an angle so you have a canting keel ...” in 50-foot seas and what happens when acres, no phones, no TV, and stinking-hot When Larsen gets going, he talks a nauti- a crew decides to mutiny in the middle summers,” Larsen says. “We grew up climb- cal mile a minute. “Put a keel on it with a of the ocean. But the truth is that when ing trees and going down wombat holes.” little wing off a model airplane—that made things are going well, there’s a lot of free But his favorite thing to do was to play in the sense to me.” time during a crossing. “We’d be belting damned-up catchment that held the fam- The obsession grew from there. In high along in the Southern Ocean or parked in a ily water supply. “One day Dad got a piece school in the ’80s he raced the newfan- high-pressure zone,” Larsen says, “and I’d of wood, sharpened the nose, stuck an ice gled Hobie Cats and reached the national be just sitting there, drawing out versions cream container on it, and sat it in the water. championships in 1984, followed by the of speed-sailing boats.” It blew to the other side,” he recalls. “That world championship in 1985. “I would The basic design he kept returning was it.” The 12-year-old Larsen was hooked. hitchhike down to the coast with my wet to was one proposed 50 years ago by an “The amount of stuff you can learn about suit on Friday night,” he says, “and sail American rocket engineer named Bernard sailing from just a sharp piece of wood,” he all day Saturday and Sunday.” Postgrad- Smith. It never caught on, and Smith died marvels. “Put a big sail rig on it: It falls over! uation, various odd jobs financed a life of in relative obscurity. But Larsen stumbled Put a sail rig on the front or the back and freelance adventuring—big-wave surfing, across Smith’s book in the back of a dusty watch it turn away. Put a heavier keel on hang gliding, ultralighting. Eventually yacht chandlery just after graduating high and it sinks. Use a lighter keel, but bend it Larsen’s motormouth and hail-fellow per- school. Discovering it, he says, was like “getting a book on jet engine flight from 1917.” Smith posed a ques- tion few had ever thought to ask: As Larsen puts it, “Most sailors A HIGH-SPEED BAILOUT think of a sailboat as something that reaches up to grab a bit of SEEMS LIKE A BAD IDEA. air,” Larsen says, echoing Smith. “But why not build it like a plane that reaches down and grabs the HITTING THE WING BEAM water?” In more technical terms, what WOULD OBVIOUSLY BREAK Smith proposed was a sailboat design that aligned the forces of sail and keel so that they opposed EVERY BONE IN MY BODY. each other more directly. From a physics perspective, every sailboat has two “wings”: the sail and sonality landed him an unpaid gig deliv- the keel. Without the keel, a boat could ering one of the first maxi catamarans, an only be pushed directly downwind. The 86-foot-long version of a Hobie, to Japan. A keel permits it to run across the wind or strategy of simply turning up at the right even point up close to the wind, so the place and time, ready to work—“with a sail becomes, aerodynamically speaking, paintbrush in hand,” as Larsen puts it—got a wing. Pushed through the water by the him more, culminating in a paid job crew- sail, the keel also generates lift and thus, in ing another maxi-cat in “The Race,” the hydrodynamic terms, is also a wing. first-ever nonstop, round-the-world sail- Yet virtually every sailboat ever made ing event. The hick from the sticks ended stacks sail over keel. The sideways lift of up as a professional sailor, “a yachtsman,” the wind on the sail is opposed by the side- Larsen laughs. ways lift of the water pushing on the keel, At the end of the 20th century the world and the boat is propelled forward. But at of high-end offshore sailboat racing was the same time there is also a rotational an especially dangerous game. Multihull force. That “turning moment,” to use a catamarans and trimarans were pushing term common to both sailing and physics, out monohulls, carbon-fiber construc- is why sailboats lean when they’re cruis- tion was supplanting fiberglass—and ing. Monohulls “heel,” while multihulls the experiments with new designs and “fly a hull.” Sailing is a balancing act. Too materials led to a lot of failures. Get Larsen much sail will overpower and eventually going and he’ll regale you for hours with capsize a boat; too little will never go any- harrowing stories about what it’s like to where. be rescued from a boat that’s breaking up Working from first principles, Smith

feb 2013 WIRED 099 where it’s all going to happen—or not. alarming to feel the boat surge ahead once again. We’ve just shed a full third of our Back in SailRocket after the dud start, Larsen hull drag. looks down what remains of the watery Larsen completes the turn somewhere runway. He’s humoring me by trying again, between 30 and 40 knots, just in front of and this time, to our surprise, the launch the sandbar. We’re out of the chop now, procedure goes as planned. We’re being and the flat conditions give us another blown sideways off the course, so Larsen burst of speed. The zodiac, which has loosens the mainsheet. The force of the been chasing us, has now fallen far behind. wind, with a little help from the rudder, Another few seconds, and a glance to the Supercavitation slowly brings the nose of the vessel around boat’s opposite side reveals that we’ve Continued from page 99 so that we’re pointing straight toward the made the third crucial transition: the beach. The wing is now pointed at the point very close to 50 knots when the lee- proposed a radical redesign. With both an wind—attached flow. She moves forward. ward pod, the one under the wing, lifts inclined mast and a similarly inclined keel, At first our progress is excruciatingly free and takes to the air. SailRocket is now and neither keel nor sail anywhere near slow. The front float is plowing, and the more plane than boat. We’re bombing the hull, it looked bizarre. But from a phys- trick foil is producing buckets of drag. But along on just the front pod and the foil. ics perspective, Smith’s design is simplic- after what seems an eternity, that front There’s not much more wetted area than ity itself. Sail and keel are parallel, facing float pops up on a plane at about 8 knots. you’d find on a boogie board, and yet canti- each other from opposite sides of the boat. This is the first crucial transition: Static levered behind that front pod is a massive Draw arrows through their respective cen- lift gives way to hydrodynamic lift. Sail machine—40 feet long and 40 feet wide. ters of lift and they point directly at each Rocket is now at its natural ride height SailRocket again surges ahead. We’re other. With the forces so aligned, there is and has dumped its first load of drag. The pressed up against the 50-knot barrier. The no turning moment. Since the boat can’t sound changes from a kind of glug-glug to wing is lifting so hard that the leeward pod tip, it can’t dump wind. More wind means a swoosh. There’s a bit of spray. is no longer flying a few inches above the more power. And more power means more We’re accelerating. With the foil down water, as it should, but is gyrating several speed. “Let it go,” Larsen says, and “it’ll rev and the wing working, the pedal is to the feet in the air. The beam that connects the until it blows up.” Writing in obscurity metal. The boat has no choice but to surge hard sail to the boat is warping and torqu- back in 1963, Smith couldn’t imagine any- forward. The swoosh of water becomes ing. It’s whipping around so fast that the thing holding together at speeds over 40 louder still, like the static between TV wing seems to be literally flapping. knots (46 mph). But Larsen realized that if channels, volume turned all the way up. My eyes, however, are glued to the foil. the boat were built with modern materials “It’s got its skates on,” Larsen says. We’re At slower speeds it’s the hydrodynamic and technologies—carbon fiber instead of running straight for the shore at nearly 20 equivalent of a brick, but Larsen’s fluid- wood, a hard wing instead of a fabric sail— knots. The sandbar is dead ahead. dynamics modeling predicts that at Smith’s design would be burly enough to Larsen drops the mainsheet and grabs around 50 knots a stable and slippery bang up against the 50-knot barrier all day the wheel. He’s concerned, but avoiding pocket of air should form just behind it. long. the sandbar is not his first priority. Now When that final transition happens, Sail Crewing on a maxi-cat that managed to that he’s got SailRocket started, his race Rocket will shed the last of its drag and set a new 24-hour speed record while cross- instincts take over. His aim is to get it to leap into speeds unknown. I can hear it ing the Pacific, Larsen decided that the go as fast as possible. He turns the wheel whine—an awful, unexpected sound like next step was to form a speed team of his slightly to port so that we’ll avoid hitting a cat yodeling in a blender—but I can’t see own. “It’s time,” he told himself. “I am the the beach; more important, it angles us much. Everything is obscured by mas- person to do this.” That was 10 years ago. closer into the wind so that the boat pulls sive amounts of spray. The foil is pulsing It’s been a decade of monomaniacal sac- harder. rhythmically, blasting spindrift and sea rifice. For a time, Larsen was scrimping Despite the fact that his instrument foam into the air like a water cannon on by, living in a steel shipping container to cluster isn’t working, Larsen carves the full automatic. save money. But he has gradually attracted turn perfectly. We accelerate the whole I glance down at the GPS unit in front enough talent and sponsorship to build way. Except for the lack of engine noise, of me: 54.4 knots. This is no joyride, I sud- two boats based on Bernard Smith’s design. I can’t believe we’re not in a speedboat. denly realize. This is the real thing. Has he The first was SailRocket Mark 1. “For me it SailRocket is starting to vibrate, hard. The done it? Has he cracked the 50-knot bar- was going full circle, back to playing on the boat’s three pods are sending up three rier? dam with little models and stuff.” Jet Ski–like rooster tails of spray. And I look up just in time to see the photog- The Mark 2 is the first to be kitted out then, suddenly, there are only two rooster rapher on the beach receding far into the with a radical new type of foil that Larsen tails—the wing has pulled the rear pod distance. “Oh shit” I think, “I’ve missed my himself designed, so it’s the real deal. The completely free of the water. I know this is cue, my Facebook moment.” But figuring job of the boat is to drag the foil up to the what’s supposed to happen at 26 knots— what the hell, I get up on my knees, one 50-knot barrier. Fifty knots is the place the second crucial transition—but it’s hand on an improvised saddlehorn (the

108 WIRED feb 2013 GPS unit) and the other waving in the air trench, creating, just for a split second, a ken the 50-knot barrier. The 54 knots was to give my best impression of Major Kong hole in the water. The faster it goes, the an instantaneous number, a brief Vmax. riding the H-bomb to oblivion: “Yeeeee- deeper the hole. But we have darted to the other side and haw!” The hole is important, because the returned unharmed. And then we crash. water flows around it. The funny-look- “This was the breakthrough run,” ing wedge foil now has a tail—made of air. Larsen announces later that evening, rais- The speed course is about a mile long, and we In cross section it suddenly takes on the ing a triple rum and Coke in one of many have reached the shallow end of the lagoon. familiar teardrop shape. But cavitation toasts to the team. “Now I know it can be There are no brakes on a sailboat, so Larsen can’t take hold of this teardrop, because done.” does the only thing he can: He cranks the its trailing edge is made of nothing. That’s wheel over hard and pops open the wing, the theory, at least. After our wild ride together, Larsen’s luck goes the sailing equivalent of a bootlegger’s Larsen desperately needs to get his foil cold. Although he makes run after run, reverse. As the boat lurches to starboard, unstuck before it’s damaged or, worse, he’s not able to repeat the 54-knot perfor- the g-forces throw me to port and, fortu- snaps. The wind is gusting, trying to spin mance. More and more, our run begins to nately, back into the cockpit. I see the world the boat around, torqueing the foil to its looks like an outlier, a black swan. Larsen rotate around me as we burn off speed and limit. “Get out! Get out of the boat!” he yells does everything he can think of to egg Sail then plow, with a carbon-fiber crunch, onto back to me. He dives over, desperately try- Rocket on. He tweaks the pitch of the foil, the shoal. We’ve run aground. The tip of ing to lighten the load to float the boat free. the angle of the wing, the ride height of the SailRocket’s foil is jammed into the grav- I follow. It’s pure chaos in 3 feet of water boat, the vector of the sails. Nothing works, elly sand. until we’re able to wrest the foil out of the and nobody can explain why getting back Hydrodynamically speaking, hydrofoils sand. Cranking the foil up to the surface on to 54 knots seems impossible. are all pretty much the same. The cross its hinge, Larsen sees that the leading edge After weeks of frustration, he resorts to section of a keel, a propeller blade, or even of his precious foil is pitted and chipped. desperate measures. He takes out a hack- saw and cuts down his foil. Six inches lighter, SailRocket peaks at 48 knots: not good enough. Another 6-inch sacri- THERE ARE NO BRAKES, fice and the speed is … still 48 knots. Finally, on the beach at SO LARSEN CRANKS Speed Spot, Larsen makes his last cut. With a full foot and THE WHEEL AND POPS a half gone from the business end of the foil, SailRocket looks like an amputee. Larsen’s idea OPEN THE WING. is that at some point the sail will so overpower the foil that WE CRASH ANYWAY. he can, in his words, “skull- drag it to a world record.” That doesn’t work either. After a TKmonth of trying, a fish all have the same elongated tear- But when he glances at the GPS readout he takes the foil and retreats to his home drop shape. Thick in front and skinny in in my cockpit, despair turns to celebra- in Weymouth, England, and thinks—for the back is just the most efficient design— tion. “Fifty-four!” he laughs, incredulous. almost a full year. His A-team of aero up to a point. At 50 knots, cavitation kicks “You’ve now gone as fast as I have ever gone dynamicists who had modeled the forces in. And when it occurs it always attacks in a boat.” The crash was nothing in light of on the boat and designed his foil were the trailing edge, because that’s where the the fact that his wedge-shaped foil worked clearly wrong. Looking for a second opin- pressure is lowest. its magic. ion, Larsen calls on a noted hydrodynam- Larsen’s trick foil—the one we have just Data downloaded from the GPS show icist who agrees to act as a B-team. “Oh rammed into the ground—is different. It that we hit a top speed of 54.4 knots and God, that’s hopeless,” he says to Larsen is V-shaped in cross section. It’s a simple raced at a sustained average of nearly 50 after he sees the foil. “There’s no way that wedge, a plow. At low speed, water gen- knots. And all that with a load of human air from the surface will suck down the erally flows around it just as one might ballast on a shortened course. SailRocket back of that at high speeds.” If there is no expect. The seas are parted by the foil’s didn’t even have its full aero-optimization air sucked from the surface, then there is leading edge and then collapse again into package on—and when we were near our no teardrop-shaped hole in the water. His a turbulent mess once it passes. At higher maximum, I was hanging out the back, diagnosis of the problem: good old cavita- speeds, however, something interesting mugging for the camera. The sub-50-knot tion attacking the back of the foil. The fix: starts to happen. The foil actually digs a average means we haven’t actually bro- a radically thinner V.

feb 2013 WIRED 109 For months, Larsen bounces revised foil ever, he’s alone. This will be SailRocket ’s to bail out in shallow water. “I ran out of designs off his new adviser. Carbon fiber? last run, and the judges are watching from runway,” Larsen says, “but I was willing “Thinner!” says the hydrodynamicist. the beach. They’re not interested in a fluky to risk it to bag that big number.” Luckily, Steel? “Thinner!” High-tensile tool steel? push through the 50-knot barrier; a Vmax he avoids grounding the boat on the shoal “Thinner still!” Until finally Larsen takes doesn’t count. They’re looking for sus- this time, thanks to the shorter foil and matters into his own hands. “Give me the tained speeds. They take an average over a higher tide. “I couldn’t have done it 20 numbers,” he says. 500 meters. That is the definition of the minutes later,” he says. Working through the math himself, he outright speed world record. Back on the beach, after checking the discovers that according to his hydro- The launch is ugly. The wind is whipping GPS, Larsen writes the digits in the sand, dynamicist’s model, his old 54-knot keel the water into such a frenzy that it’s actu- from right to left, in reverse order, in front couldn’t possibly have gone more than 28 ally swallowing the bottom part of the wing. of the rest of the team. Seven. Three. Dot. knots. The A-team analysis on the other “It was well underwater, and the whole Five. Six. A record-smashing 65.37-knot hand, predicted that it would go at least 65 boat was rolling to leeward like it was try- run! Even Larsen can’t believe it, at first knots. Neither team—PhDs all—could get ing to capsize,” Larsen says afterward, “and mistaking that 500-meter average for the it right. Digging deeper, Larsen figures out then I heard something go pop.” Something peak speed. But the peak was 67.74 knots. why. Underlying all the models, the com- had broken. It was time to abort. But when “All the way home I’m just thinking of plicated equations, and the computational Larsen starts to turn back, the boat sud- all the people who didn’t see this coming,” fluid-dynamics programs were just a few denly catches the wind and starts moving. Larsen says. His revolutionary new keel old scientific papers from the ’60s and With the acceleration, the leeward float shape means all the sailing records are up ’70s. “Theorists can read a paper and get pops out of the water, starts to plane, and for grabs again: the round-the-world, the one thing out of it,” Larsen says, “and you pulls the bottom of the wing out of the drink. trans-Atlantic, the Transpac, the 24-hour. can read it and get something totally dif- There is the first crucial transition. Larsen’s run makes the record-breaking ferent out of it.” To go or not to go? That is the ques- monohulls, maxi-cats, and trimarans of the It dawns on Larsen that if the theorists tion. “Was that carbon fiber?” Larsen asks richest of the rich obsolete. “They’re old. can’t even agree on their theories, much himself. No, he decides. When something Just old,” Larsen marvels. “Things are com- less make an accurate prediction, than all structural breaks, you can usually feel the ing now that will put those boat designs the fluid-dynamics software in the world boat shudder as the load gives way. He fig- with the square riggers.” can’t design a high-speed foil that will ures that what he heard was the wing’s When I traveled to Namibia a year work. “All these big computers, all these delicate skin starting to rip. “Nothing before, I had met a daredevil yachtsman pretty pictures,” Larsen says. “But at over looks too bad,” Larsen thinks after swivel- with his eyes on a big prize. But now that 50 knots they haven’t been verified. They ing his head around to assess the damage. he has it, all Larsen can talk about is the haven’t been checked against anything He goes for it. “No more dicking around. hydrodynamic frontier. “What we are dis- real.” Garbage in, garbage out. We’re out here to do 60.” covering is that things are not as black- “The foil we used on that 54-knot run Even with the rip in the wing, the boat and-white going through this barrier as we was the wrong size; it was the wrong accelerates through one transition after thought they were,” he says. The mixture shape,” Larsen tells me. But it did yield another. The rear pod starts to fly at 26 of air, vapor, and very high speed water valuable data. “We put a point on the knots. The leeward pod flies at 50. Because wrapping itself around a boat at the limit graph,” he says, “against which everyone of the abortive start, he’s forced to take a is dynamic and extremely hard to model can calibrate their machines, their math- line very close to the beach. It’s a nearly by computer or even simulate in a high- ematical equations, their theories.” identical repeat of the run on which I speed flow tank. To understand it, you must Post-calibration, the foil that Larsen’s was along for the ride. Again, the leeward explore it directly, through experimenta- A-team came up with was still a thick pod—even with the rip at the end of the tion. You need SailRocket. V-wedge of carbon fiber, albeit subtly dif- wing—starts to fly too high. “Is something Larsen is too modest to call himself a ferent in its angles and about half the size really broken out there?” Larsen won- scientist. But when he talks he no longer of the one that got stuck at the 50-knot ders, second-guessing himself. The steer- refers to SailrRocket as a boat—it’s a “lab- mark. The B-team hydrodynamicist quit ing feels loose, as if there is going to be a oratory.” Speed Spot is no longer a race- in a huff, not wanting to be associated liftoff soon. As the boat keeps on acceler- course—it’s a “wind tunnel.” And he has with certain failure. Larsen returned to ating through the 50-knot barrier, Larsen been dreaming of a whole host of new foil Namibia to put the new foil to the test— clenches: “Just hold it! Just hold it! Hold it! designs. There are tiny ones that could this time in front of the World Sailing Hold! Holdholdholdhold it!” slide along in a giant underwater bubble Speed Record Council, the official govern- At 58 knots, the leeward pod under the of vaporized seawater like the Russian tor- ing body of speed sailing. wing, which is supposed to just skim the pedo does. There are bigger V’s that can water’s surface, is 4 or 5 feet in the air. plow a trough so wide that at 50 knots one Almost a year to the day after our harrowing “The only thing that that would make it whole side of the foil would be completely run, Larsen is again floating at Speed Spot, fly that high is speed,” Larsen realizes. dry—3 feet underwater. “We’ve had the strapped into SailRocket with the wind Stopping is going to be a problem. As in test-pilot phase,” he says. And sailing has blowing a steady 30 knots. This time, how- the 54-knot run, the late start forces him had its first sonic boom.�

110 WIRED feb 2013