Seakeeping behaviour of a damaged warship

The unfortunate event that a naval vessel is damaged, decisions must be made regarding the reduction in the vessel’s capability and what damage control procedures can be initiated to both restore this capability and minimise further damage. In order to make an informed decision, it is vital that Commanding Officers (COs) have access to reliable information regarding the vessel’s structural integrity, stability and seakeeping performance. A reduction in any of these parameters may have a significant influence on the operability of the vessel. A preliminary program of work has been conducted to investigate the change in ship motions due to an angle of list induced on the vessel after sustaining damage. This study incorporates both experimental and numerical simulations of a listed vessel at rest in a seaway. During the experimental program several parameters were investigated to ascertain their influence on the vessel's motions. These parameters include initial list angle, direction of list and wave conditions. The results from this study show that for a vessel in beam seas there is no significant effect on vessel motions due to an angle of list. However, in head seas the introduction of an angle of list has a marked effect on the amplitude of roll motions. The example operator guidance generated shows that numerical modelling can be applied to the analysis of the operability of a vessel against set limiting criteria. This information and methodology could be incorporated into a rapid damage assessment tool along with sea-load predictions to assist COs in their decision making process in the event of an emergency.