Parallels of yaw and roll dynamics of ships in Astern seas and the effect of nonlinear surging

Abstract

In the first part of this paper we consider in parallel the roll and the yaw dynamics in astern seas and we point out a number of interesting fundamental dynamical analogies between the two modes. In the second part we focus on the roll dynamics, especially the parametric and the pure-loss mechanisms; however taking into account nonlinear surging effects. Analytical solution for the nonlinear surge motion is proposed. Moreover, characteristic graphs showing the quantitative effect of surging on capsize tendency are presented. Other aspects considered are, the effect of restoring modulation based on two frequencies and the dynamic effect of an initially hardening restoring. © Springer Science+Business Media B.V. 2011.