Ship Motion Instabilities in Coastal Regions

Ship motion instabilities occur much more frequently in coastal regions than in the deep ocean because both nonlinear wave-wave interactions and wave-current interactions increase significantly as the water depth decreases. This is particularly significant in the coastal regions connecting to the open ocean, since the wave resonant interactions change from the four-equivalent-wave interaction in deep water to the interactions of three local wind waves with a long wave (e.g. swell, edge waves, bottom topography waves, etc.) in shallow water [1, 2], resulting in rapid growth of the incoming long waves. In this study, we use our DiSSEL (Digital, Self-consistent, Ship Experimental Laboratory) Ship Motion Model [3,4,5,6] coupled with our Coastal Wave Model [1,2,11] and an Ocean Circulation Model [7] to simulate strongly nonlinear ship motions in coastal regions, focusing on the ship motion instabilities arising from ship body-surface wave-current interactions.