Chapter 11 - Flooding and Damage Condition

Abstract

Ships can be damaged by collision, grounding, or enemy action. A vessel can survive damage of some extent if the hull is subdivided into watertight compartments by means of watertight bulkheads. The subdivision of merchant ships should meet criteria of international conventions. After flooding, the waterline should not be above the margin line, a line passing 76mm under the bulkhead deck. Warships are subject to requirement defined by the respective navies. There are two methods for finding the parameters of a flooded ship: the method of lost buoyancy and the method of added weight. An important design aid is the curve of floodable lengths. For a given position along the ship, say P, the floodable length is the maximum length of a compartment with the centre at P, whose flooding will not submerge the vessel beyond the margin line. New regulations refer more and more to a probabilistic approach. The ship safety is characterized by an index based on all possible damage scenarios. This index is compared with a required safety index.