A COMBINED STEADY-STATE AND TRANSIENT APPROACH TO STUDY LARGE-AMPLITUDE SHIP ROLLING MOTION AND CAPSIZING

An innovative technique to analyze the critical rolling motion of a sh ip in a seaway is described. It combines two previously described tech niques into a single integrated one which allows the analyst to identi fy critical dynamical behavior and then to study its consequences in g reat detail. The first step in this procedure is to determine the vess el steady-state behavior using numerical continuation methods. The eff ect of vessel damping and righting arm are then investigated. Once a v essel configuration has been finalized, the critical wave amplitude an d frequency condition is then determined and analyzed in detail using Poincare mapping techniques. This combined approach should be useful i n developing rationally based ship stability criteria and guiding mode l tests and numerical simulations of critical vessel capsizing behavio r. Although random wave forcing is not specifically considered herein, the work could be useful in identifying critical peak spectral freque ncies that should be avoided.