Flooding protection of Ro-Ro ferries

Abstract

The survival capability of damaged ships under dynamic sea conditions has been the subject of technical investigations since the early 1 9W's. Building upon this base of knowledge, a research program was initiated in Canada to investigate the prime factors affecting the survival of Ro-Ro passenger ferries when flooded symmetrically after damage at midship. This effort would form an initial phase in the development of criteria for assessing Ro-Ro capsize safety after damage in sea states. A comprehensive model test program was devised to systematically examine the capsize phenomenon in sea states up to 7 metres significant wave height, using a model which replicated the design characteristics and proportions of large Canadian flag ferries. The vertical centre of gravity of the model was varied over a range of test conditions which met SOLAS 90 damage stability criteria. Using time history traces and summary data sheets, the test results were analysed to identify patterns of repeatable behaviour. Examined were the maximum upright and minimum capsize conditions of the ship in each test case. Prime variables used to make assessments under dynamic sea conditions are metacentric height and dynamic stability in the damaged condition. conclusions are drawn using these prime variables with respect to their relationship to residual freeboard after damage, freeing port area and presence of a centreline casing. In addition, findings are made on the behaviour of water accumulation on the vehicle deck which may assist in establishing criteria serving to design for capsize prevention in the future.Peer reviewed: YesNRC publication: Ye