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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.
$700 million is comparable to what you'd pay to construct a brand new cruise ship. And what they'd end up if they renovated the United States wouldn't be a cruise ship, it'd be an ocean liner.
The difference between a liner and a cruise ship is this: a liner is built to perform regularly scheduled service between ports. Even if the seas are high and there's a storm blowing an ocean liner still goes out because her purpose is to get her passengers to point B when the schedule says they'll be there. So an ocean-liner has to be built to be very fast and very seaworthy.
When air travel supplanted sea travel the companies who owned ocean liners repurposed them for leisurely pleasure cruising. However for this purpose ocean liners are over-built in certain respects and under-built in others. A cruise ship doesn't have to be fast, or shed high seas or stand up to gale force winds. What she needs to do is to take as many people and amusements as possible, at a leisurely pace, into as many interesting places as possible.So cruise ships look nothing like the elegant ocean greyhounds of old like the SS Normandie or the SS United States. A modern cruise ship is basically a top-heavy motorized barge which, despite having jaw-dropping dimensions, can squeeze into shallow harbors that normally can't handle big ships. And they're pokey, even by the standards of 1930s ocean-liners. Cruise passengers aren't really paying to go places, they're paying to spend time on the ship. The ship's ports of call are just for breaking the monotony of incessant luxuriating.
At present there is only one active vessel in the world that is capable of providing true liner service: the RMS Queen Mary 2. Although she resembles a modern cruise ship in her amenities she carries relatively few passengers (2700) for her size (79,000 tons) and cost ($900 million). For a hundred million less you could have a pure cruise ship that carries 1/3 more passengers, and into shallower harbors too. She couldn't sail around the Horn in July in the teeth of a winter gale, but the market for that particular experience is somewhat limited.
Looking at the article, one of the concerns that led to abandoning the SS United States project is the stability of the ship. So clearly they weren't restoring the United States to her original 1950s configuration. That was stable enough but only provided 1900 berths, and those in conditions that while elegant enough would be spartan by modern standards. You wouldn't have swimming pools, bowling alleys, planetariums, or any of the other ridiculous things modern ship designers throw in to astonish and delight their customers. These people must have wanted to transform the SS US into a kind of hybrid liner-cruise ship like the QM2. For that they'd have add space for a lot more passengers along with all the amenities they'd expect on their very expensive vacation. Since you can't make the hull bigger, that means building up. Way up.
Even if they succeeded in the technical challenges of squeezing all that stuff into the hull, the commercial viability of the project is doubtful. There is no practical need in this world for a vessel like the QM2; her sole reason for existing is thrilling customers who are so jaded that an ordinary extraordinary ship just won't do. Only an unique ship will.
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