STAB1994_Mathematical Modelling of Motions and Damaged Stability of Ro-Ro Ships in the Intermediate Stages of Flooding
H. Vermeer, A.W. Vredeveldt and J.M.J. Journée, Mathematical Modelling of Motions and Damaged Stability of Ro-Ro Ships in the Intermediate Stages of Flooding, STAB 1994, Melbourne, Florida, U.S.A. / DUT-SHL Report 1021-P
Mathematical Modelling of Motions and Damaged Stability of Ro-Ro Ships in the Intermediate Stages of Flooding
H. Vermeer (DGSM), A.W. Vredeveldt (TNO), J.M.J. Journée (DUT)
It is generally recognized that the phenomenon of a “rapid capsize” during the intermediate stages of flooding may represent a potentially dangerous situation to a ship. This is particularly true for a roll-on/roll-off (Ro-Ro) ferry sustaining a “high energy” collision due to the lack of subdivision on the car deck. In order to analyse the associated safety problems, a mathematical model has been developed with the aim to describe the actual motion behaviour and the associated residual stability of a ship in the time domain after sustaining a collision damage. This prediction instrument has been validated to a great extent by model experiments for a pontoon with cross-duct connected wing tanks and a typical ferry with a few different damage orifices and in addition various compartment configurations.
An outline of the mathematical model and the corresponding computer program is presented, discussing in particular the dynamics involved during the ingress of water with due emphasis on the importance of the instantaneous roll angle and the effect of subdivision arrangements on the distribution of floodwater. Further the results of a study on the parameters involved, such as the configuration of the damage orifice, and systematic calculations carried out for a number of existing Ro-Ro passenger ships yielded a number of conclusions relevant to the inherent safety of such vessels after a high energy collision. These conclusions address the validity of calculations for regulatory purposes traditionally based on quasi-static considerations, the actual occurring angle of heel in relation to possible shift of cargo and the effectiveness of several subdivision alternatives.