Stability of a tumblehome hull under the dead ship condition

Some methods for direct stability assessment under the dead ship condition were currently developed by the international maritime organization(IMO)under the Second Generation Intact Stability Criteria.Model tests and simulations are carried out to validate the numerical methods used in assessing the stability under the dead ship condition.This is done in three stages.Firstly,the uncoupled roll mathematical model(1 DOF)is adopted to calculate the roll motion based on the irregular beam waves and the steady wind.Secondly,a drift free experiment is conducted to measure the roll motion under irregular beam waves with zero speed,and then two restrained experiments with counter weights and four springs are performed under the same condition.Finally,the effects of the drift and sway motions on stability under the dead ship condition are then verified by experimental results,and the results of the numerical methods are compared to the results of the model experiments.It is concluded that more accurate numerical methods could be developed for assessing the direct stability under the dead ship condition.