Chaotic Behavior of Ship Swaying Motions in Irregular Waves

In this paper, the nonlinear mechanism of ship swaying motions in irregular waves is analyzed; the frequency spectrum plot, recurrence plot, 3-dimension phase portrait are exhibited of the ship motion time series and several key parameters, namely correlation dimension, Kolmogorov entropy and the largest Lyapunov exponent are calculated. The chaotic behavior of ship swaying motions in irregular waves is demonstrated qualitatively and quantitatively which provides theoretical basis and method for short term prediction.