If you think man's ingenuity knows no bounds ...

[jimpeel]

you're right.

You say you'd like your cruise ship to be 73 feet longer? Just cut a check for £30million and give us six weeks.

http://www.dailymail.co.uk/news/art...t-shut-cruise-ship-sliced-half-add-rooms.html

Pictured: The 'cut-and-shut' cruise ship that was sliced in half to add more rooms

By Neil Sears
Last updated at 8:23 PM on 25th August 2008

It sounds like an unforgettable magic trick - sawing a cruise ship in half.

But this is no illusion, as the owners of this 916ft liner really did cut it open to extend its length by 73ft.

Such measures may seem extreme, but the £30million cost of the job is just a fraction of the £500million - and years of labour - needed to launch a new ship.

Construction crews worked around the clock for two days to saw the ship in half

This remarkable extension to the giant cruise liner, called the Enchantment of the Seas, provided 151 more cabins.

The overhaul also added new facilities, such as suspension bridges over the pool deck, as well as trampolines and a 108-seater restaurant.

As the cruiser is 12 decks deep, construction crews had to work around the clock for six days to divide it in half.

Abracadabra: The ship was then welded back together

They used blow torches and circular saws, and even cut a swimming pool in two along the way.

The painstaking process took place in a dry dock at the Keppel Verolme shipyard in Rotterdam, Holland.

There, the new 12-deck high, 3,000-ton mid-section was carefully moved into place with hydraulic jacks and 18-wheel lorries, using lasers to keep things exact.

The new piece of the ship was then welded securely into position - with 1,300 individual cables, pipes and ducts having to be reconnected.

Take one ship: The Enchantment of the Seas before the makeover

Within six weeks, the Enchantment of the Seas was back in service again. It is currently in the western Caribbean after setting sail from Fort Lauderdale in Florida.

And the extra capacity - which came on top of the 3,000 passengers and crew it could previously hold - is certainly needed.

Cruise holidays are becoming increasingly popular in Britain, and across the Western world.

Not only that, but a younger generation of sailors are increasingly jostling for cabin space with the pensioners who have traditionally filled such ships.

The attacks on the World Trade Centre in 2001 and subsequent terrorism threats have made holidaying at sea increasingly attractive to those who are afraid to fly.

A spokesman for Royal Caribbean, which owns the ship, said: 'We've committed ourselves to providing innovative, exciting and unexpected experiences for our guests.

'We are willing to stretch ourselves and our ships - literally - to fulfil that promise.'

 

[Inkara1]

How strong are those welds? Are there reinforcements to strengthen the ship at the new joints? The article doesn't go into those details.

 

[jimpeel]

Apparently this happens quite a bit. It is far more economical to refurb an existing ship than to start from scratch on a new one.

Basically, the welds are not just around the periphery of the hull. They are on every wall, floor, and ceiling of every new compartment. I'm sure that there are also reinforcing rods which couple the parts together. Adding this section is no different than what they do when they join the prefab sections to a new build except they likely don't start from both ends and put the last section in the middle.

 

[A.B.Normal]

How strong are those welds? Are there reinforcements to strengthen the ship at the new joints? The article doesn't go into those details.

well since it was welded together the same way when originally built,why the need for reinforcing?

 

[jimpeel]

well since it was welded together the same way when originally built,why the need for reinforcing?

I'm sure that there are ereinforcing rods used to couple the prefab sections on new builds also.

Back in WWII the Kaiser victory ships had this fatal flaw in which they had a propensity to simply break in half in rough seas and go down in seconds.

What they did was to simply weld a beltline of steel down the sides of the ships and the problem went away.

http://www.americanheritage.com/articles/magazine/it/1988/3/1988_3_26.shtml

Another problem with the Liberty was a scary tendency to crack—usually in cold weather and in rough seas. One summary of an accident aboard a Liberty crossing the North Atlantic in March 1944 states: “A loud report, followed by two smaller ones, was heard .… Immediately afterward, the forward end of the ship separated from the after end and floated away.” Few Liberties actually split in half, but hundreds sustained cracks in their steel plates. When reports started reaching the press, there was no shortage of theories: poor workmanship, too much cargo, or substandard materials. The most widely held theory was something called “locked-in stress.” This held that welding always sealed a certain amount of heat-related stress into a structure and that this stress could escape later to break the ship apart. The Navy convened a panel to find the cause.

What they found is still important to ships being built today, according to J. Harvey Evans, a professor emeritus of naval architecture at the Massachusetts Institute of Technology. “It turned out that the simplest way to solve the problem was to change the composition of the steel,” says Evans. Carefully controlling the ratio of carbon to manganese in the steel plate made the steel tougher.

A contributing problem lay in the original design of the Liberties. Stress was gathering at a few weak points and causing cracks that spread faster than the speed of sound. When a ship rides the waves, the hull bends up and down at the center, depending on where the waves are. The upper decks of a ship absorb a lot of the tension and compression this bending causes; unfortunately these decks are interrupted frequently by openings for ventilators, stairways, and hatches, and stress carried by the steel deck has to detour around these holes. Round holes are safest, because stress runs smoothly around circles without bunching up excessively. But the Liberty had hatch openings with businesslike square corners. Invisible lines of stress gathered at these sharp corners. Of the serious fractures suffered by Liberties, about half started at hatch corners. Another quarter started at a notch in the ship’s side near the deckhouse that was there to make room for a ladder.

Welding was indeed part of the problem, because a welded ship is a continuous, single piece, while a riveted ship is really a bunch of plates sewn together. A crack running through one riveted plate comes to a halt at the edge and has to begin all over again at the adjacent plate. A crack in a welded ship, on the other hand, can pass effortlessly through a weld to the next plate and the one after. But retreating to an all-riveted ship was out of the question. The solution adopted was rounded corners and braces at weak points. Liberties also got riveted seams at key points to stop the spread of cracks. Altogether the number of ships suffering fractures each month (several types of freighters, not just Liberties, shared the cracking problem) fell by more than 80 oercent after the changes were made.

The important thing about the Liberty fractures, adds Professor Evans, is that this was the first time ship designers really got a close, thorough look at a given ship’s performance. The population of these nearly identical ships was so large that everything that could happen to a ship happened. Liberties were exposed to horrible conditions: decks were overloaded; the ships plunged through the worst storms; they took torpedoes and bombs. Some Liberties survived attacks that would have sunk earlier freighters.

 

[Professur]

Most new ships are built in this fashion .. assembling large prefab slices and modules built offsite, saving valuable .. and expensive drydock time. Even the new nuclear subs are built in this way.

 

[chcr]

How strong are those welds? Are there reinforcements to strengthen the ship at the new joints? The article doesn't go into those details.

If the welders are any good at all the welds are stronger than the surrounding metal.