Nonlinear Time-Domain Simulation of Ship Capsizing in Beam Seas.

Abstract : Ship design practice has been to measure stability by static criteria and to compensate for dynamic effects through a margin of safety. However, there is a fundamental difference between static and dynamic stability. Certain factors which result in favorable static stability characteristics may actually present greater danger when considered in light of a dynamic analysis. The traditional linear strip theory method is not suitable for assessing ship capsizing. This report presents a state of the art nonlinear simulation method, LAMP (Large Amplitude Motion Program), for the evaluation of ship operation in extreme seas. The intent of the study was to mode! maritime casualties, including a time domain simulation of a ship capsizing in beam seas. A 400-foot (122-meter) Series 60, C sub B = 0.7 ship with the center of gravity, CG, located amidships and 2.07 ft (0.63 m) below the design waterline is used as an example in this study. This ship satisfies the U.S. Coast Guard's minimum Metacentric Height, or GM, requirement for large cargo ship. It is shown in the report that capsizing can happen due to dynamic effects even for ships that satisfy the minimum GM requirement.