Should cruise ships have a double hull ?

Considerations on the Costa Concordia accident

The recent accident involving the cruise ship Costa Concordia on the Italian coast of the Giglio Island is producing the usual questions that arise after any disaster affecting human lives. It is the question of whether the safety of the facility in question is sufficient, be it either a ship, aircraft, train, skyscraper etc. Clearly there is not a complete safety in any order of life, but it is also clear that any current safety level can be improved and the issue is deciding when and where the laws and regulations governing safety are to be changed to get better expectations.

History teaches us that mankind is learning the hard way. When we suffer a great accident is when we consider that perhaps safety provisions are not adequate and should be analyzed in detail and realism to decide whether they should be improved.

In the case of ships we have the super-known historical case of the Titanic. Her loss led to a strong review and modification of the conditions in flooding resistance a passenger ship should afford. The crash of the Costa Concordia is not fully comparable to that of the Titanic, in the number of lost lives, but both have in common that the sinking was ultimately due to their inability to withstand, afloat and in stable condition, a breach in their outer shell and inner structure that caused the ship flooding and sinking.

Several friends of mine have asked me why the Costa Concordia sunk and although the exact and complete causes will not be known until the final official report be completed and published, one can say now that the ship hit a reef, laterally along a large length below the load line, resulting in a tearing of the shell plating that produced the flooding of more compartments than she can withstand as planned in the ship design, undoubtedly following the applicable rules.

We can recall that a few decades ago some accidents involving oil tankers and the subsequent large oil quantities  dumping to the sea, with consequent environmental disasters, led to the mandatory adoption of increasing subdivision of cargo spaces of such ships, through the provision of a double bottom and double hull throughout their length, which previously were not required nor usually adopted, because of the involved cost.

Passenger ships, like the Costa Concordia, do have a double bottom but not a double hull throughout their length and it is clear that its adoption would lead to increased capital costs and technical difficulties in the arrangement of ship spaces.

The catastrophe of the Costa Concordia makes me wonder if something similar will arise in passenger ships. The damage suffered by the Costa Concordia seems of little extension perpendicularlly to the hull but very long lengthwise. A double hull would have prevented such a large flooding  so as to sink the ship? Impossible to say at this moment, but it could be possible.

We wait to see the investigation in the Costa Concordia event and its possible impact on the hull design regulations of cruise ships and similars.