The supercharged Allison V-12 explodes into life, its exhausts firing smoke and flame as the unlimited hydroplane shakes like a plesiosaur on meth. A gleaming prop then shoves the wooden beast onto plane, where at 100 mph the boat dances on the tips of its front sponsons, half its propeller, a cushion of air, and a prayer. And as I found out last year, things only get dodgier from there.
Inside its cockpit, Miss Thriftway, an exacting replica of a famed 1956 American Power Boat Association Gold Cup winner, offers no seatbelt or rollover protection—just a huge steering wheel, some gauges, switches, and a go pedal. Translation: Only luck will save you if the monster spins or flips and bucks you clear. Which happened a lot during the first two decades of unlimited hydroplane racing, when nearly a dozen top racers were killed. “The sport was deadlier than war,” remarked Tom D’Eath, a retired champion.
Our drive in the 1600-hp race boat, which occurred at the annual Mahogany & Merlot event last October at Lake Chelan, Washington, started as loud, breezy excitement. This ceded to exhilaration, and as the hydro kept accelerating, to something resembling alarm, and finally terror. Factoring together the wind and noise, plus the rolling, pitching, and yawing of the hull, being jammed inside the cockpit felt like cowering in a foxhole during a 9.0 earthquake.
We’ve all gone fast in cars, confident that if something goes wrong, steering and brakes can correct it, and should those fail, there’s always seatbelts, and maybe airbags or a cage. An unlimited hydroplane, though, rockets our flimsy bodies to un-survivable speeds, largely unprotected, and our brains know it. And so, in a quixotic moment in the Thriftway, I realized that while we’re fearing death, we’re also feeling most alive. Triple digits in an unlimited hydroplane, friends, is fully living.
***
People have raced motorboats forever, with America’s first Gold Cup in 1904 in New York predating the Indy 500 by seven years. Top-shelf hydroplanes continue today in the form of the H1 Unlimited series, with turbine engines delivering breathtaking performance—some say too quietly—in enclosed-canopy boats. In between were the golden years from 1950 to 1970, when artisan builders campaigned a new form of boat, the three-point hydroplane, which instantly and audaciously replaced traditional planing hulls.
Half boat and half airplane, these 7000-pound unlimiteds were akin to Indy roadsters of the same period—a zenith of postwar engineering and outright daring on water. Designed by Ted Jones, the “prop riding” unlimited hull consists of two broadly spaced “sponsons” (think of seaplane floats) that frame an air tunnel below. As velocity builds, so does air pressure below the boat. Result: maximum speed, minimum drag. It’s pure genius, and the principles are still followed today.
Building one started with a pair of 28-foot oak stringers, tapered at the bow and spaced wide enough to drop the engine in between. To these stringers were bolted a dozen lateral oak frames, bolstered by battens of oak or spruce—like prewar wooden airplane construction. Last came lightweight okoume plywood outer skins, bedded in a seam compound, with sheet aluminum covering the lower “wetted” surfaces. Sourced from WWII aircraft, the 2000-pound V-12 nestled inside was anchored by eight large bolts and rigged with a dozen lines and linkages for fuel, oil, water, throttle, and spark. It was such a tidy setup that engines could be changed at the races in 20 minutes. And teams often did, typically burning through a unit or more per race weekend.
At rest, the 12-foot-wide bow rides just 3 inches above the water. Once the boat accelerates past about 70 mph, lift under the hull—and the downward propeller thrust—picks the transom out of the water, reminiscent of a tail-dragger airplane accelerating to takeoff. The dynamics create a stupendous rooster tail of spray 40 feet high and 120 feet long when approaching top-end (160 mph in period, 130 mph in exhibitions today).
Miss Thriftway co-owner Dane Sorensen explained that these boats can get unstable at high speeds, especially when the water gets choppy. The design lacks quickly adjustable control surfaces; if the bow drops or lifts, or if a hull edge catches wrong, you’ll instantly enjoy one of the most violent crashes imaginable. The thinking was: Either strap in and risk drowning if the boat lands upside down or get thrown out and hope to live through the trauma. In period, drivers opted for the latter. And yet, films and photos still show guys being flung from the boats like a medieval trebuchet heaving boulders over a castle wall.
So who in the hell would race these things, anyway? “A good number were owner-drivers who were mechanically inclined and hands-on in the building and care of the boats,” Sorensen mused. “Along with huge confidence, there was also a certain arrogance in the drivers that could be polarizing. But while they were risk-takers, they were not careless.” Sorensen knows something about this firsthand. While shoeing it around the Chelan course, he was twice asked by organizers to slow down, as the Thriftway was visibly unstable. “I have to respect that,” he admitted later. “These boats could bite you in the ass back when, and they can still bite you today.”
Either strap in and risk drowning… or get thrown out and hope to live…
After retiring from unlimiteds, three-time Gold Cup champion D’Eath dove into Formula cars, racing Super Vee against Al Unser Jr. and others. “The water is a constantly irregular surface, especially if you get off-line,” he noted. “Learning how to read it took years, which is why you’d never see a young unlimited driver—they were late 20s or early 30s at the earliest.” Dixon Smith, race engineer and owner of the 1962 Miss Bardahl, raced by late champion Ron Musson, added, “World War II pilots were used to the speed, liked the challenge, and weren’t intimidated by the risk.” Alternatively, some unlimited drivers were simply teachers; one was even a milkman.
Sadly, virtually everyone who raced the early round-nose boats has passed on. “I think Bill Muncey was maybe more of a showman than anything else,” said Fran Muncey of her late husband, an eight-time Gold Cup winner. “He loved performing in front of people.” Mary Henley, the widow of 1974–75 Gold Cup champion George Henley, recalled that in the early decades, unlimited hydroplane racers were the second-highest insurance risk—behind astronauts. “You would not have guessed George as a driver—he was a quiet, unassuming guy,” she reflected. “But when he got in the cockpit, he was primed and ready. They all loved the competition and going fast, like they had daredevils in their blood. I know it had to be something like that, because it sure wasn’t for the pay.”
***
Wearing a red racing suit, an orange life jacket, a high-visibility orange helmet with goggles, and rocking long red hair and a beard and piercing blue eyes, Sorensen looked more Viking warrior than boat racer. He stood on the floating dock and motioned me aboard, beside the tailfin; thanks to its wide beam, the hydroplane did not rock side to side. From there, I stepped into the cockpit—a temporary bench replacing the normal deeply padded single bucket—placed my left foot on an aluminum dead-pedal, and leaned into the gunwale as Sorensen hopped aboard. Overstuffed in our apparel, there was zero spare room; in fact, with nowhere for my right arm to go, I was told to drape it around Sorensen’s back. Fishing for something, anything, to hold, I clutched the shoulder of his uniform. A huge open exhaust collector bristled at most 3 feet from my head.
Crew members angled Miss Thriftway away from the dock while Sorensen initiated the starting drill. After flipping the master electrical switch, he set both magnetos to light the Allison’s 24 plugs and activated the 24-volt fuel pump to send 22 psi of 100-octane avgas to the ginormous “pressure injection carburetor”—actually, a sophisticated aviation air meter. With the pump whining loudly, Sorensen confirmed the fuel mix handle was set to the “idle cutoff” (starting) position, then toggled a primer circuit to spray fuel directly into the intakes while thumbing the starter. The steps matched how the heroic pilot of a Lockheed P-38 Lightning, which originally carried this engine, would have begun a mission in Sardinia, North Africa, England, New Guinea, or France in 1944.
Laboriously, the 1710-cubic-inch (28.0-liter) Allison began turning like a great mechanical beast, its 48 valves yawning open via gear-driven overhead cams and roller rockers and the coffee can-sized pistons stroking a half foot in their bores. The gear-driven supercharger force-fed air and fuel into the combustion chambers, which processed it all at an appallingly slow speed. Until… a burly chuff! emanated from one header with a swirling wisp of brown smoke. And chuff! chuff! as two more cylinders spat fire into the pipes. Then nothing but the whining fuel pump again. The challenge of starting this wartime relic explains why more than a few combat pilots became unlimited hydroplane drivers—they could master the engines.
Patient during the no-start, Sorensen waited 15 seconds before re-priming the intakes and retagging the starter. The engine whined again, multiple cylinders caught in quick succession, and the hydroplane jumped away from the dock, washing the crew with a burst of water and twin plumes of exhaust. Swiftly, Sorensen turned the mix handle to “full rich,” carefully throttled up, and eyeballed manifold pressure—the boost shoved into the engine by the supercharger. The gauge climbed to 35 inches (17 psi) as the revs topped 3000. (To avoid explosive overboosting, teams carefully match supercharger setup to the engine, gearbox, and propeller.)
The boat is direct drive, and while the engine is busy gulping 1 gallon of fuel per minute, the 13-inch two-blade prop whirls at three times crankshaft speed. Honed finer than Excalibur, at 10,000 rpm, it streaks the sky with torrents of spray, the sunlight sparkling through droplets like the tail of a comet. From inside the boat, though, the sound of a WWII fighter dominates—big and booming, it’s the full-throated cry of a huge motor hard at work. The sound frequency is lower than any car, even a dragster. You know because you not only hear it but feel it rattling your chest cavity, urgent and threatening.
***
Unlimited hydroplanes often ran on 3-mile ovals in period; this one was 2 miles around, and Sorensen punched Miss Thriftway toward the far turn. Between startup, accelerating onto plane, and top speed (I observed 115 mph on the speedometer), the sound, windblast, and vibration built to hurricane levels. Some riders, I learned later, panic and demand an immediate return to the dock—which is how I lucked into this ride…
Admittedly, whipping up triple digits in a modern car—especially on a racetrack—isn’t that big a deal, thanks to the secure, predictable tire grip on asphalt. But in a hydroplane, you’re literally flying with restless water underneath, no brakes—and shockingly vague steering.
Say “Charge It!” with a smile, and take the ride.
Sorensen passed the first buoy and entered the corner without lifting, and after a powerful Norseman’s turn of the wheel, the boat reluctantly began vectoring left. He then quickly lifted the throttle, and something magical happened—the boat’s tail dropped and began sliding outward to begin the long, 180-degree hairball turn. From here, the whole game changed as the hull slipped, rocked, and lurched as its beveled chines (lower edges) bit the water. Back on the throttle, Sorensen wrestled the wheel to keep the boat rotating—like a dirt-tracker, I thought. Along the way, the engine revs and noise leaped and bellowed like a mad rodeo bull.
Three laps into Mr. Toad’s Wild Ride, driver Sorensen motioned for me to take the wheel, while keeping his foot on the gas. This was wholly unexpected as I’d dared not even ask. The experience was unlike a car or motorcycle, where the steering can feel light and responsive. Instead, steering the Thriftway seemed like trying to crank open a flow gate on Hoover Dam—hugely heavy with virtually no feedback other than struggling to move the rudder against frightful hydraulic pressure. A furtive glance at the speedometer mid-turn proved nearly useless because the world was shuddering so hard, but the needle hovered around 85 mph as the boat drifted and—clumsily at first on my part—followed the racing line. Luckily another boat ran just ahead and to the left, so the main task was keeping outboard of its rooster tail.
While spectators experience almost poetic or symphonic beauty as the boats race by, inside a vintage unlimited hydroplane awaits the most atrocious human environment possible: the massive pipes thundering, the gearbox and supercharger howling, the valvetrain thrashing, the wind shrieking, and the spray whipping—all these sounds and sensations topped by combustion heat and the thick smell of racing oil. But there’s more, because the pounding of the hull, sponsons, and chines as the boat slashes through the chop feeds directly into the cockpit. There might be a point, after hours of experience in vintage hydros, where you’d feel comfortable being shaken like a rag doll in a wild terrier’s jaws. But that was impossible in a few laps aboard Miss Thriftway on a one-time basis.
***
Reportedly, the dozen or so usable three-point, round-nose unlimited hydroplanes extant—a few replicas included—might trade for $200,000 to $1 million, depending on specifics. Why so much, you might wonder. For starters, just 100 or more early round-nose unlimited hydroplanes were built through 1970, with a couple dozen known to exist today. Likewise, after WWII, leftover new Allison V-12s cost just a few hundred dollars, but they are $100,000 or so in good shape now, with later Rolls-Royce Merlin and Griffon engines double that. Crazy though it sounds, this means unlimited engines can cost nearly as much as the boats. This assumes you can find one, because the warbird community also needs motors, and the owners of those multimillion-dollar aircraft tend to have some coin. Bottom line, for arguably the greatest classic boating experience, that’s the price of power.
On the contrary, you might ask: Why so cheap? After all, many vintage race cars cost more. Surely hydroplane prices are tempered by the practicality involved. “Owning an unlimited is like owning your very own elephant,” admitted Hydroplane & Raceboat Museum (thunderboats.org) executive director David Williams. “If you bought one, you’d immediately ask: ‘Where am I going to put this thing? It eats everything,’” he said with a laugh, adding that for infrastructure, you’d need at least a 60-by-40-foot shop, a tilt trailer and hauler, a machine shop, special tools, spares and supplies, and an experienced crew. Plus, crane service to hoist the boat from trailer to water and back wherever you run it. “Going from zero to a functional operation is a big mission.”
Upon buying a vintage unlimited hydroplane, you’ll instantly become the caretaker of a unicorn. Most were lost to crashes, fire, dismantling, or decay and neglect after their careers finished. Unlike steel race car chassis, which can withstand poor storage for decades, the unlimiteds’ construction was more vulnerable to rot than a Volaré in a Vermont vineyard. Not because wooden boats can’t live for centuries, but because hydroplanes weren’t designed that way.
That said, once screwed and glued together, the hull became a formidable wood monocoque—heavy and strong, at least for a time. A famous calamity happened to Muncey in 1958, when his early Miss Thriftway lost a rudder in Seattle’s Gold Cup and the boat speared a 40-foot U.S. Coast Guard utility, sinking it within minutes. “I think he’s the only fellow since the Spanish-American War to sink a U.S. military vessel in peacetime,” joked historian Mike Fitzsimmons.
One of the lucky boats is the 1962 Miss Bardahl, owned by engineer Dixon Smith, which earned three Gold Cup titles in four years and then retired. Ignored as technology progressed, it shuffled between owners and then languished outdoors until 1997, when Smith bought it. Mother Nature treated the racer harshly, and even though the Bardahl was highly complete, Smith and his team still replaced nearly three-quarters of it during restoration.
As this illustrates, a central problem for unlimited hydroplane survival was physical size, which deterred permanent dry storage. As a result, the classic unlimiteds seen today are often the aquatic equivalent of George Washington’s hatchet. As well, because teams swapped boats as budgets and affiliations allowed, many changed names and paint schemes during their working years; a Miss Madison seen today may have been the Notre Dame or the Miss Exide decades before. The engines are even more faithless, again with teams buying, selling, and trading them at will. Incidentally, Smith noted that wartime metallurgy was so good, most original engine components are still in use today, from magnesium cases and forged crankshafts to pistons, rods, and camshafts.
***
Way too soon, Sorensen reclaimed the wheel, throttled down, steered around an exit buoy, and aimed toward the dock on a modest plane, the V-12 growling impatiently. Clearly the thrill ride was over. I was partly relieved, for self-preservation reasons, but mostly disappointed that we hadn’t gone faster, and quite selfishly that I hadn’t gotten to drive more.
After he switched back to idle cutoff, the boat settled into the water like a bossy trumpeter swan. Sorensen then killed the fuel pump and mags, and Miss Thriftway glided quietly toward the dock, where crew members captured it with poles, deck shoes, and lines. He climbed out first, adroitly. Less gracefully, I only managed to perch on the seatback, rattled and simmering in the experience. I’ve seldom been so overwhelmed by a drive, other than road-racing a Kawasaki Mach IV in 1974 and testing a Le Mans GTS car in ’99. Once again after 25 years, though, I needed to compose myself.
Vintage unlimited hydroplane owners often take riders at their events—for a price. The typical cost is $2500, which may seem high until considering that buying your own boat will put you upside down quicker than a Hobie Cat at Haulover Inlet. To infect yourself most economically, attend the next Mahogany & Merlot (mahoganyandmerlot.com) or a similar event, say “Charge It!” with a smile, and take the ride. You’ll remember it forever, and thanks to GoPro technology, you can order a video to show your buddies.
No, I didn’t buy the video—writing this tale hammered it in my head instead.
Hoisted into and out of the water like wooden plesiosaurs, the round-nose unlimited hydroplanes of 1950–70 were capable of nearly unfathomable speed—getting up to 200 mph in straight-line record runs—as well as bone-shaking violence.
Measuring 28 feet long and weighing 7000 pounds, they were hand-built from oak, spruce, and okoume plywood, an African hardwood that was both light and strong, ideal for the broad decks. Screwed and glued together, the hulls were covered underneath with sheet aluminum, necessary to keep punishing water pressure from ripping the hulls apart at aircraft speeds. That’s not just hyperbole—the hydroplanes literally flew above the surface, with just the tips of the front sponsons (outer hulls) and half the propeller touching God’s heavenly waters.
Nesting inside were WWII warbird engines, often 1710-cubic-inch Allison V-12s as in this unit, a replica of the 1956 Miss Thriftway. Supercharged and later turbocharged and nitrous-boosted, in period, they cranked some 2500 horsepower. Heroic skill was required to keep the boats on course—and off the shoreline of the lakes and rivers that hosted Gold Cup events. Only an estimated 100 were built.
Tailfin
Incorporating a marine plywood skin over oak framing, the 4-foot tailfin is partly functional, part visual appeal. The trim tab helps keep prop thrust from walking the boat sideways.
Cockpit
Steering requires herculean strength, as there’s no power assistance. Instrumentation includes a tachometer, fuel-, oil-, and manifold-pressure gauges, and a low-oil-pressure warning lamp.
Engine
The Allison V-12, sourced from a P-38 Lightning, has gear-driven overhead camshafts, 48 valves, a supercharger, and metallurgy so good that most of its 1944 components are still in use.
Deck
The shapely design of the three-point, round-nose unlimited hydros was complemented by lovely hardwood decks. Painted in this case, the wood’s natural beauty is protected by clear sealer on some hulls.
Non-Trip Chines
Boats sliding sideways are in the danger zone for flipping over. To reduce this risk, the sides of the sponsons and hull (“chines” in boating parlance) are chamfered, allowing the wake to spill off the sides instead of “tripping” the hull.
Bottom
To protect the vulnerable wooden hull, 6061-T6 aluminum sheets fastened with hundreds of wide countersunk screws cover all wetted surfaces.
Skid Fin
Fitted to the back of the left-hand sponson, this aluminum dagger helps the hydroplane hold the line in high-speed counterclockwise turns. Its shape and dimensions are boat-specific.
Propeller
Stepped up 2.5 to 3 times via an oil-cooled gearbox, this two-blade forged 4340 steel propeller turns at some 10,000 rpm. When the boat is trimmed correctly, at high speeds, only its bottom half is immersed.
Rudder
Controlled by a long rod and pitman arm, the high-tensile 4340 steel rudder extends nearly 2 feet underwater. Located on the left side of the transom, it’s out of the prop wash to help the boat turn hard left. Incorporated are water pickup feeds for the big V-12.
This story first appeared in the July/August 2025 issue of Hagerty Drivers Club magazine. Join the club to receive our award-winning magazine and enjoy insider access to automotive events, discounts, roadside assistance, and more.
Great article! You put us with you in the cockpit. You also covered your history of the sport and terminology very nicely. Thanks
