An integrated approach to damage ship survivability assessment
This research concentrates on damage ship stability and means for assessing dynamic ship performance in this state. A consolidation of many approaches for tackling damage ship dynamics has been undertaken, culminating in the development of a numerical tool for simulating ship behaviour while accounting for progressive flooding and the ensuing effects of floodwater motion. General features that have been accounted for in a new purposely developed numerical program PROTEUS3 include the following: Linear concepts regarding intact ship hydrodynamics based on strip theory and Rankine source method (RSM). These are further utilised by convolution and spectral transformations in deriving relevant time domain force realisations. Non-linear excitation/restoring forces calculated from pressure integration up to the instantaneous undisturbed wave profile. Non-linearities in hydrodynamic properties arising from variation of mean underwater geometry due to occurrence of non-stationary asymm etries in mass distribution are taken into account by a database approach. Forward speed in arbitrary heading. Progressive flooding through a ship with any internal subdivision and floodwater motion simulations based on free-mass-on-potential-surface (FMPS) model. Non-linear treatment of the effects of cargo shift or floodwater motions on the overall ship dynamic behaviour. The underlying modelling has been explained by rigorous derivation of all the relevant equations from first principles. Validity of the model has been tested comprehensively through comparison with available physical model tests data. A thorough investigation on the new effects of modelling advancements concerning the accuracy of the developed model has been undertaken and the results are presented and discussed. Despite the introduction of simplifying assumptions concerning floodwater behaviour, the predictions show consistency with physical experimental data. It is believed that this pragmatic approach constitutes a very efficient tool for predictions of vessel performance in extremely adverse conditions. This effectiveness has been demonstrated by undertaking forensic analysis of two of the most controversial accidents of the last two decades, namely the loss of MV Derbyshire and the NW Estonia disaster.