Effect of Watertight Subdivision on Damage Stability of Ro-Ro Ferries

Abstract

Effect of various subdivision arrangements of ro-ro vessels on damage stability is discussed. The arrangements included single and double sides both below and above the car deck, with and without a double buoyant car deck, and with or without a watertight tween deck below the car deck. This gave as many as 16 various arrangements for each compartment length. The double sides both above and below the car deck are of the same width b = 0.1B. The double bottom, when not flooded, worsens damage stability. The car deck and tween decks should be ‘openwork’, to be transparent for water and air. Otherwise, the ship can capsize at the very initial stages of flooding. Double sides and a double car deck together improve considerably damage stability, both in terms of maximum arm and range. A new characteristic was introduced, termed the critical deck height. Flooding a deck above the critical height leads to a rapid capsizing of the ship.