HOMOCLINIC CONNECTIONS AND PERIOD DOUBLINGS OF A SHIP ADVANCING IN QUARTERING WAVES

The large-amplitude motions of a ship running in waves are analyzed wi th a mathematical model reduced to a system of eight coupled nonlinear ordinary differential equations. Bifurcation analysis in relation to the surf-riding condition, with control parameter the angle of the rud der, shows the existence of a region of oscillatory behavior, containi ng also a chaotic domain. This region ends with a homoclinic connectio n and a dangerous jump toward the overtaking-wave mode, which can incu r ship capsize. Addition of linear control removes the chaotic domain while giving rise to new regions of oscillation. (C) 1996 American Ins titute of Physics.