Study on Ship Motions and Capsizing in Following Seas (Final Report)

Abstract

Critical situationsleading up to capsize are pointed out for a ship in severe following and quartering seas by using the aid of numerical simulation program.The effect of several parameters on the critical situation is discussed to investigate the possible causes of capsizing.In addition, Froude-Krylov force acting on a ship with large amplitude displacement are evaluated in the practical formulas to make simulation program simple.

Enhanced estimation method and approximation method of the PDF of roll angular acceleration and jerk in beam seas

“…Let f (t) be denoted as P(t). The parametric excitation terms adopted in this section are calculated by first obtaining the GM variation, which is calculated from the computed restoring arm GZ for each regular wave height with a ratio of the ship length and wavelength of 1 (λ /L = 1) based on the Froude-Krylov assumption [43]. This GM variation is then combined with the time series data of Grim's effective waves to obtain the parametric excitation term P(t).…”

Broaching probability for a ship in irregular stern-quartering waves: theoretical prediction and experimental validation

“…Hamamoto and Akiyoshi [10] and de Kat and Paulling [11] in late 1980s independently developed 6 DOF mathematical models combining strip theory and maneuvering models for capsizing and broaching. Umeda and Renilson [12] developed a 4 DOF mathematical model based on a maneuvering model with roll coupling and linear wave forces under low-encounter frequency assumption.…”

Nonlinear dynamic analysis of the course instability of ships in wind and waves

“…Therefore, the calculation of the total Froude-Krylov excitation loads requires the integration of the fluid pressure over the submerged portion of the hull. When neglecting the nonlinear 2 nd order terms, Froude-Krylov excitation loads for the ship are written as: According to Hamamoto et al (1991), by employing a strip theory we can define derivatives of the pressure with respect to the displacements in surge, sway and heave. These "pressure" derivatives integrated appropriately correspond to the Froude-Krylov forces and moments.…”

“…These "pressure" derivatives integrated appropriately correspond to the Froude-Krylov forces and moments. Therefore, in line with Hamamoto et al (1991) methodology, by using the "pressure" derivatives and Gauss theorem, Froude-Krylov forces and moments can be defined as volume integrals of the form:…”