[QUOTE=AustralianPilot;66476]Burong,
This link will give you an idea on modern cruise vessel watertight/fireproof bulkhead layout in addition to other relevant information. If you scroll right you will find a key to identify the different areas.
http://dvo.free.fr/techdatas.htm
Double hulled vessels also have their own problems with regard to reduced stability (raising of the centre of gravity), maintenance issues with corrosion between the two skins and in the event of this significant allision on CC, it is highly likely that the inner shell would have been bilged. Of course…any changes to construction regulations will take a great deal of time and not protect existing tonnage.
AP.[/QUOTE]
Thank you, AP
I now understand the whole thing much better than I did before, thanks to your most helpful link.
I also watched the TV programme again last night. The programme makers did not discuss whether extending the double-hull further upwards might cause other problems for other reasons. They just implied that it ought to be done with cruise ships, which led me to shout at the screen, “Wouldn’t it just be easier to ensure that a cruise ship cannot/does not get into a ‘Costa Concordia situation’ in the first place?”
In the UK at the moment, there is a huge amount of “Titanic Hype” because it is now so close to the centenary of her sinking. (The night of 14/15 April 1912, apparently.) So the programme irritated me because Concordia did not hit an iceberg in 1912! Also, the programme contains the usual ghastly allegations that Capt Schettino might have “freaked out” and done nothing useful, plus the usual allegations that Capt Smith (the Master of the Titanic) was equally useless when push came to shove.
However, an American man who is a marine expert commented that if a ship the size of Costa Concordia hits a rock even at slow speed, it is going to cause serious damage just because of the ship’s weight etc. He seemed to be hinting at exactly what you have said, which is that extending the height of the double-thickness hull would not necessarily have made any material difference to what happened in Concordia’s initial allision with the rock.
They then showed a [I][B]long[/B][/I] ribbon of very thick-looking steel that had been ripped right off Concordia’s side and ended up on the bottom - very similar to what one sees when one opens a tin of corned beef, only giant. It is sort-of curled up on itself but if it were stretched out it would obviously be very long.
I must say, I thought, “If this rock could have caused so much damage to such thick steel, would an inner hull really have been able to prevent a problem?”