Experimental investigation on stability of intact and damaged combatant ship in beam sea

The stability of the damaged ship is influenced by several factors including the encountered waves and its response to them, the floodwater behaviour and its interaction with the ship’s motions. The behaviour of floodwater is highly nonlinear and therefore the model testing is one of the best ways to assess the actual behaviour of the damaged ship. The present study addresses mainly the experimental study of the stability in intact and damage condition of a combatant vessel in beam waves. The tests were carried out at the Kelvin Hydrodynamics Laboratory of the University of Strathclyde, using a model of the well-known DTMB 5415, equipped with a double bottom. A 1/51-scale model was used. Free rolling decay tests with and without restricted constraint were implemented in calm water, with the model restrained at the bow and stern during the wave excited oscillation tests. In order to investigate the performance of the damaged ship, an opening was made at the starboard side near the midship through which two internal compartments were flooded. The obtained results show how in the damage condition and the floodwater dynamics the compartments impact on the motion responses of the ship and forces acting on the ship’s hull. Nonlinear behaviour of the RAOs of all tests are given to provide the benchmark results for prediction with CFD methods further.