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Shipping News and information / Re: Six Dead After COSTA CONCORDIA Runs Aground

« on: January 15, 2012, 09:23:58 PM »

Second ....100 years after Titanic's tragedy, it seems our Naval Engineers should be taken back to school if their projects cannot maintain such a monster perfectly leveled when water comes in. The modern ship projects are said to contain the water in the damaged compartment perfectly leveled in order to prevent the tilting to one of the sides...Can anyone help me to understand if this is not true ? In a ship that is 290m in length, 60m opening is too much for the structure to stay leveled ? I wondered if that opening would have been done by an Iceberg like in the titanic case in deep waters or by a hit from a tanker or other huge vessel. It would mean that the 112.000t liner would be now resting in the bottom of the ocean somewhere and a tragedy with more casualties would have happened for sure.

The comparison with Titanic is apt in that the length is similar (269 m versus 290 m for Concordia) while the rupture in the hull also has a similar length (90 m).
That is more than 30% of the ships hull, damaging more than 3 adjacent compartments.

In damage stability calculations the maximum damage length is much smaller. All compartments are so designed that when damaged, water automatically distributes over the width of the ship (normally U shaped compartments), so no pumps are involved in this.
The remaining intact part of the ship provides sufficient stability to keep the ship upright.

Should however more than 3 compartments become flooded to such an extent that the bilge pumps would not be able to keep up then that is the equivalent of wings falling of an aeroplane, it's the end of the line.

So a gash of 90 metres is simply too much, for Titanic as well as for Concordia.
 

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Shipping News and information / Re: Six Dead After COSTA CONCORDIA Runs Aground

« on: January 14, 2012, 05:16:50 PM »

She's actually on her starboard side as the pictures clearly show.
The last position plots on the AIS show her approaching Giglio island at more than 15 knots which she would have to pass either on the west or east side in order to proceed to Savona, her destination. This seems like a navigational error.
The track and position relative to the island seems consistent with a gash on the port side.

Passenger vessels are normally designed in such a way that any water entering a compartment is equally distributed over the width of the vessel so that it doesn't develop any list (this would prevent life boat deployment). The design should allow for sufficient damage stability for a 2 or 3 compartment flooding.

However, damage over such a multitude of compartments exceeds the ships stability capacity.

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Shipping News and information / Re: Six Dead After COSTA CONCORDIA Runs Aground

« on: January 14, 2012, 02:19:49 PM »

Regarding survivability of damage to her port side. Some reports say that there is a gash of 70 metres in her shell plating below the waterline. That would be consistent with hitting a pinnacle or rock with some speed.

Normally passenger vessels are calculated with a 3 compartment damage scenario, meaning 3 adjacent compartments flooded. However it is almost certain that a 70 metre damage length exceeds the distance between two transverse bulkheads (resulting in 3 compartments flooded). More likely that 4 or 5 adjacent compartments were flooded, beyond survivability of the vessel.

On the bridge this would have been visible with the bilge alarm system, so the captain would have known his ship was doomed and headed inshore.