MOL Comfort was less capable of dealing with lateral loads
The design of the "MOL Comfort" was less capable of dealing with lateral loads than similar post-panamax container vessels, a ClassNK investigation has found. Although the design of the ship performed as well as its peers against International Association of Classification Societies (IACS) specifications for vertical bending strength of the hull girder, the "MOL Comfort" performed significantly worse than its peers when lateral load effects were taken into account.
The ClassNK investigation considered possible differences in declared and actual weight of containers, possible deviations from the nominal yield strength of the steel used, and the effect of possible deformations in the girder.
Those deformations considered were from manufacture, permissible within Japanese shipbuilding standards, and deformation during service as observed on the sister ships. These uncertainty factors were an improvement on the methodology of a previous investigation by Japanese Authorities, which concluded that the hull girder was strong enough to sustain the conditions the "MOL Comfort" faced at sea.
The more thorough parameters were fed into a simulation and the vessel's design was compared to seven other ships of 6,000 TEU and 8,000 TEZ designs in 3-hold model elasto-plastic analyses. The models analysed the designs' performances in two high stress scenarios - one where an entire bay is left empty of containers, the other where the ships has low ballast, both of which increase the stress on the hull girder.
The investigation found that it was possible that the vertical load on the hull girder exceeded its limits by a narrow margin. Results of the investigation will be made available to other classification societies and submitted to IACS with proposals and suggestions to related IACS rules.
The design of the "MOL Comfort" was less capable of dealing with lateral loads than similar post-panamax container vessels, a ClassNK investigation has found. Although the design of the ship performed as well as its peers against International Association of Classification Societies (IACS) specifications for vertical bending strength of the hull girder, the "MOL Comfort" performed significantly worse than its peers when lateral load effects were taken into account.
The ClassNK investigation considered possible differences in declared and actual weight of containers, possible deviations from the nominal yield strength of the steel used, and the effect of possible deformations in the girder.
Those deformations considered were from manufacture, permissible within Japanese shipbuilding standards, and deformation during service as observed on the sister ships. These uncertainty factors were an improvement on the methodology of a previous investigation by Japanese Authorities, which concluded that the hull girder was strong enough to sustain the conditions the "MOL Comfort" faced at sea.
The more thorough parameters were fed into a simulation and the vessel's design was compared to seven other ships of 6,000 TEU and 8,000 TEZ designs in 3-hold model elasto-plastic analyses. The models analysed the designs' performances in two high stress scenarios - one where an entire bay is left empty of containers, the other where the ships has low ballast, both of which increase the stress on the hull girder.
The investigation found that it was possible that the vertical load on the hull girder exceeded its limits by a narrow margin. Results of the investigation will be made available to other classification societies and submitted to IACS with proposals and suggestions to related IACS rules.