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A whoosh as good as a wish
Hugh Whall
October 28, 1968
Smaller and more powerful than other marine engines, Thunderbird's water jet has one disability: its price is a bit more than $40,000
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October 28, 1968

A Whoosh As Good As A Wish

Smaller and more powerful than other marine engines, Thunderbird's water jet has one disability: its price is a bit more than $40,000

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As a weekend pleasure boatman, what would you say to an engine that ran more economically at high speeds than at low, that developed more horsepower than your current power plant but weighed far less and was far smaller, that burned cheap oil instead of expensive gas, and that made fallible appendages like rudders, drive shafts and propellers unnecessary? The obvious answer is: don't ask foolish questions.

As a matter of fact, however, the question is not so foolish, for a Utopian power plant meeting all those requirements and designed for the amateur boatman actually exists. For some time now the citizens of Miami, many of whom must have thought a drunk was loose on Biscayne Bay in a shiny 32-foot power cruiser, have been witnessing its trials.

Whoosh! First it would start, then stop; back then fill, aimlessly turning this way and that as if its befuddled driver couldn't find the right control. On occasion it would swing out of Government Cut and head for the rippling Gulf Stream beyond Miami Beach, where its drunken maneuvering would continue in ever-tightening figure eights. Frequently, like some airborne Keystone Cop, an agitated helicopter could be seen chasing the demented craft. But the helicopter's bubble was filled with staid engineers from Pratt & Whitney Aircraft, the company that built the engine that drove the boat in those seemingly crazy circles.

The boat itself, Formula 322, built by Thunderbird Products Corp., bears the distinctive stamp of Race Driver-Designer Jim Wynne. In her cockpit is the customary steering wheel, dashboard, seats and cabin companionway, but instead of the bulky, raised engine boxes which usually cram fast powerboats, there is delightful emptiness. The uninformed passenger might suppose the new boat was powered by nothing but wishes.

Bolted neatly beneath her cockpit deck, however, there lies a comparatively tiny but power-packed turbine and water-jet propulsion system which—to boatmen accustomed to clanging pistons, erratic fuel and ignition hookups, dragging rudders and vulnerable propellers—is as good as any wish.

The engine itself is nothing new. It is the marine version of a United Aircraft turbine that has powered everything from buses, trucks, trains and helicopters to the racing cars Andy Granatelli entered in the Indianapolis 500. Called a free turbine, it is a distant cousin to the JT4 engines which propel commercial jets and bombers. Unlike diesel and gasoline piston engines, whose thirst for fuel increases with power and whose lives get shorter the longer they run at full bore, free turbines grow more economical and durable the harder they're pushed. In boats—where engines frequently run for long periods at full throttle—the advantages are obvious. Furthermore, so reliable are turbines that airlines have found they need tear down such engines only every' 12,000 hours or so instead of the every 4,000 hours demanded by piston engines. Indeed, the airplanes themselves are likely to wear out before their engines.

But the turbine power plant alone is not what makes the Thunderbird's boat such a potential dream-come-true; it is the combination of the turbine engine with a Pratt & Whitney water-jet propulsion system. The men aboard New York City's fireboats have long known that when you stand on deck and aim a high-pressure hose at a fire on shore, your boat tends to move back away from the blaze. The fireman's hose is nothing more than a water-jet propulsion unit, and the pump that pushes the water through it could be powered by a turbine.

In Thunderbird's new Formula 322, the turbine drives an efficient, compact rotary pump that spins at 2,100 rpm to suck up sea water from beneath the boat and spew it out of a nozzle at the stern with sufficient force to drive the 32-foot boat at more than 40 mph.

"We were worried at first that the thing would wash down other boats or docks that got in the way," says Wynne, "but we soon found we could aim the jet down far enough so as not to bother anyone."

To steer the boat, the driver aims the nozzle right or left and to reverse he lowers a metal deflector flap that shoots the stream forward underneath the hull, thus pushing the boat backward.

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