London: DNV’s conclusion as a result of its extensive investigation into the MSC Napoli accident in January 2007 is: The accident’s cause is not a general problem for the container shipping industry at large. However, minor structural modifications have to be made to a very restricted number of the existing container ship fleet.
Related directly to the MSC Napoli, DNV concludes that the buckling strength in the forward part of the ship’s engine room was insufficient.
In addition, the newbuilding rules and procedures are being looked at, and DNV has invited all members of the International Association of Class Societies (IACS) to cooperate on a unified approach to dealing with the newbuilding rules.
On 18 January last year, the hull girder of the container ship MSC Napoli collapsed. The ship was at that time in the English Channel, some 70 kilometres off the UK’s Lizard Point. All 26 crew members were rescued safely, while the ship was beached the day after in Lyme Bay, close to Branscombe.
Olav Nortun, DNV Maritime’s technical director, explains: “As the vessel’s class society, our best resources – both people and cutting-edge computer tools - were put on the job from day one. We’ve left no stone unturned and I’m convinced that this accident and the investigation following it have made the shipping industry even safer.”
The loading caused by the ship itself, its containers and the harsh weather exceeded the capacity of the hull girder and caused the ship to break in half just aft of the forward engine room bulkhead. The critical area was where the longitudinal stiffening of the cargo area ended and the transverse stiffening of the engine room started.
None of the existing container ships classed by DNV has to stop operating. Only two ships have to be strengthened. “This is a minor structural modification which may be done afloat and only involves a small amount of steel,” explains Olav Nortun. “Alternatively, the still water bending moment may be reduced by modifying the loading conditions.”
Based on DNV’s findings, the probability of an accident like that involving the MSC Napoli recurring is very small. The damage statistics for container ships are very good. In addition, the investigation has shown that the strength of this particular ship was less than that of similar vessels.