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Luxury Liner SS United States Cannot Be Put Back In Service (miamiherald.com)
tomhath writes: Once the fastest ocean liner ever built, the SS United States has been mothballed for almost 50 years. An ambitious project to refurbish the SS United States as a luxury liner has been abandoned due to insurmountable technical and commercial obstacles. Plan B, to turn it into a floating hotel/convention center, might go forward. Miami Herald provides some history of the SS United States in its report: "The iconic 1950s vessel, which was bigger than the Titanic and once carried celebrities across the Atlantic Ocean, was set for a $700 million overhaul by the Los Angeles-based luxury line, which also has offices in Miami. The SS United States was decommissioned in 1969 and has been gutted and docked in Philadelphia for two decades on the Delaware River. On its maiden voyage in 1952, the ship traversed the Atlantic in three days, 10 hours and 42 minutes -- a record it held until 1990."
" fitted with diesels sized for aircraft carriers"
Aircraft carriers do not use diesels. Maybe some Jeep carriers and ships like LPH but not the big carriers.
They uses massive steam turbines and yes the USS United States used a power plant very much like the one used in the first generation of US super carriers.
From http://www.ss-united-states.ne...
"Propulsion: The ship was able to attain such a high rate of speed due to an unrivaled power-to-weight ratio. The SS United States was a quadruple screw vessel, powered by 4 Westinghouse steam turbines, rotating at 5240 rpm, which produced up to a combined 247,785 shaft horsepower (SHP). Today's nuclear powered aircraft carriers only produce slightly more power than this. Her oil-burning boilers could reach 1,200 degrees F, causing the turbines to spin faster than than any ship of her day. The Big U could steam for 10,000 miles without stopping to refuel. The SS United States was a mere 28 feet shorter than the Queen Mary, but due to the extensive usage of aluminum in her superstructure (2,000 tons) weighed only 53,290 tons, roughly 30,000 tons less than the Queen Mary. The SS United States was such a success that its hull and engine designs were placed in nearly all large naval battle ships, and the ship itself was the prototype for the first super aircraft carriers, the Forrestal class. On the Big U, the powerplant was slightly derated because boiler superheat temp was lowered from 1,000 degrees to about 925 in the interests of reliability/maintenance. The Carriers actually generated 5,000 to 10,000 SHP per shaft more than the Big U. The propulsion system was a closely guarded secret until the 1970s. "
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
It's not that astonishing. The main speed constraint on a displacement hull like an ocean liner's is the bow wave. As a ship moves forward, the water it pushes aside has its pressure increased slightly, so it bulges upward at the bow. What goes up must come down, so this bulge eventually drops down to sea level, then overshoots and drops below sea level. This is called a bow wave. The key here is that this motion of this wave is dictated purely by the physics of the water (and the water depth, but that effect is small enough it can be ignored in the ocean). And that the front of this induced pressure wave is stuck to the bow of your ship (it's a standing wave when viewed from the ship), hence why it's called a bow wave.
I'll skip the math, but the net effect is that at slow speeds, your ship is moving through multiple waves of its own creation and stays relatively level. But at a certain speed called the hull speed, the wavelength almost exactly matches the length of the ship, and the bulk of the ship's mass sinks down into the trough of its self-induced bow wave. At that point, your ship is basically trying to power itself "uphill" through the water (opposite of surfing), and the energy required to move faster increases dramatically.
There are two ways to bypass this problem.
This is also the rationale for the bulb underneath the bow of large oil tankers and cargo ships. It's location underneath the water slightly forward of the ship makes the water act as if the ship is slightly longer (the bow wave starts earlier), allowing it to eek out a tiny bit more speed at the same amount of wave resistance.