BBC Focus Magazine

[Jamie]

How do you turn over a 952-foot cruise ship that’s capsized on a rocky shoreline?

Marine engineers around the world are speculating on the best way to refloat the Costa Concordia, an operation that will begin as soon as authorities account for all the missing passengers

http://news.discovery.com/earth/concord ... 21701.html

[M Paul Lloyd]

Well, its not as if they can wait for a good tide to help float it off!

Personally I'd try inflating air bags in as much of the flooded part of the hull that could be safely reached, then attach two or more really powerful tugs and stand well back?

[Lateralman]

Par buckling may do too much damage. After patching up and emptying. I think I would attach a series of long water bags stretching the full length of the ship. On the exposed side of the hull that is out of water, around the area of the gash, and then fill them with seawater to act as a counter balance to drag it over. Then get two tugs and give it a pull.

[Lateralman]

The water bags strung out along the side of the ship would look like a string of sausages and be attached from the deck by rope or chain. They could be used in conjunction with airbags placed under the other side of the hull.

[M Paul Lloyd]

Trouble is the side that is underwater is hard up against the rocky bed it ran onto. So attaching bags of any kind to the outside is going to be problematic at best. I would much rather use the holes already in existence and those cut into the hull during the rescue efforts. Go in with floatation bags and airlines, back off to a safe distance and pump as much air in as they will take. Then, when its sufficiently afloat drag it off the rocks before attaching external bags.

Its a lot of work and a hell of a lot of bags, airlines, compressors, barges, cranes, standby rescue craft and divers (with everything they will need) to worry about, but I can't see a workable alternative other than just cutting it up where it lies.

[Lateralman]

Therefore, as a combination, if all the holes were patched and the water pumped out below decks and made watertight wouldn’t that make it sufficiently buoyant enough to lift the keel off the rocks to make use of water counter weights to right it.
In addition, instead of using tugs to drag it off would a couple of aircraft carriers provide more pulling power?

[Lateralman]

Actually, I am not concerned about salvaging the ship. I do not think that they should cut it up. Before every possibility is exhausted, to recover the missing people. There is always hope, so ideally the ship should be righted intact.

[Lateralman]

After patching up the holes and pumping out. How about positioning a powerful tug at either end, bow and stern, ready to drag it off the rocks and out to sea. However, before they do so, another large ship is sent at full speed passing along the full length of the liner in order to create a large wave. When the wave hits the liner, it should lift it enough, for a short while, to raise it so the tugs can pull it free.

[Lateralman]

For additional lift, perhaps a series of very large helium balloons can be attached to the full length of the hull.

[M Paul Lloyd]

Your imagination knows no bounds does it Lateral?

Tugs are designed for purpose and can generate far greater pulling force per tonnage than any other type of craft. Also sealing all the holes would be very complicated, dangerous and prone to catastrophic failure if anything went wrong whereas bags, inside the hull, would keep the air where it was needed.

Balloons are prone to the vagaries of the wind and creating waves would be difficult so close to a rocky shore and would create unpredictable results, indeed it could make things very much worse.

To effect a proper recovery the entire hull needs to be afloat and as upright as possible, so it can be safely towed to a dry-dock, otherwise they run the risk of turning one disaster into several new ones.

[Lateralman]

I refuse to abandon ship Mr Lloyd. You would have thought a resolution for coping with this sort of disaster was already there to implement. If I can think of anything else to help, (however wacky) I will post it.

[Thinker]

I might be repeating what's already being said, but I'll put it in a simpler way.

Step 1: Patch up any holes on the ship where water can ingress into the ship.

Step 2: Pump out all of the water from inside the ship.

Step 3: Pull the bugger back up with tugs boats or something like that.

Step 4: Then all should be well!

Anyway that they decide to do it is going to be expensive, that's just something they have to live with. But if they are planning on repairing it and sending it out on future voyages, my plan is probably the best way.

[M Paul Lloyd]

Step 1: Patch up any holes on the ship where water can ingress into the ship.

The problem here Thinker is that much of the flooded side of the ship is underwater and resting on a jagged rocky sea bed, so access is extremely limited. Plus such sealing would require a lot of welding which would be difficult under any circumstances and if such welds were to fail, well it would all be for nothing.

Step 2: Pump out all of the water from inside the ship.

Filling air bags inside the ship would have much the same effect.

Step 3: Pull the bugger back up with tugs boats or something like that.
Step 4: Then all should be well!

But I'll fully endorse both of these suggestions.

[Jamie]

I imagine the fuel tanks are still intact and sealed, so won't pumping out fuel will give some additional buoyancy (providing they replace it with air rather than water).

[M Paul Lloyd]

They could indeed Jamie, although I am unsure as to how much gaseous pressure they are designed to take?
Could be a tricky one.

[Lateralman]

They have stopped the search... Sad.

[Jamie]

They could indeed Jamie, although I am unsure as to how much gaseous pressure they are designed to take?
Could be a tricky one.

I would think air at relatively normal atmospheric pressure would do the trick. I don't know what method they'll use to pump it out though.

Mind you, it's 114,000 tonnes, so the 2300 tonnes of fuel might not make that much difference.

[M Paul Lloyd]

They are relativley small aren't they Jamie. But my main worry about pressure is that the hull would have to withstand sufficient pressure to expell the water to a depth of 18 metres and still hold that pressure during the righting process.
Airbags could help take some of the strain in that respect.