Full scale container ship cross section loads - first results

A measurement campaign is being carried out onboard a 9300 TEU container vessel. The measurements comprise ship performance parameters, cross section loads on two locations, local stresses in the bow area and accelerations on five longitudinal locations on deck. The wave environment was monitored by a wave radar analyzing the back scatter from the waves and by two level height radars on the bow. The deformation of the vessel in waves is determined on basis of the accelerometer signals. These deformations are transferred to local loads using a global FE model of the ship. Results for a measurement in storm conditions have been compared to direct measurements of the strains showing a reasonable agreement. It appears that in this storm there is a very significant contribution of the flexural deformations of the ship on the vertical bending moment; the high frequency signal has an amplitude of about 50% of the wave frequent loads. No such high frequent contribution was measured on the torsion deformation, while this was expected since the vessel sailed in bow quartering conditions. It is suggested that a reason could be the high damping in this deformation mode due to the stacks of container, but more measurements must be analyzed to support this suggestion.