Bifurcation Analysis of Ship Motions in Steep Quartering Seas, Including Hydrodynamic “Memory”

Steady-state ship dynamics in steep harmonic waves encountering the ship from stern quartering direction is under investigation. Bifurcation analysis is performed by applying a numerical continuation method. Stationary as well as periodic states are traced, as selected control parameters are varied. Regions with coexistence of different ship responses are identified. The main novelty of the paper lies in the extension of the continuation analysis to a 6-DOF model, for a quartering sea environment, with inclusion of memory effects within a potential flow framework. Complete, vessel-specific stability diagrams, for horizontal plane motions, are produced in an automated and time-efficient manner. These could provide useful guidance to ship masters for avoiding the occurrence of surf-riding and broaching-to.