Three-Dimensional Imaging of the High Sea-State Wave Field Encompassing Ship Slamming Events

Abstract

Understanding and modeling ship wave slamming necessitates characterizing the surface wave field that results in slamming events. Shipboard measurements of the incoming wave field were made during sea trials of the twin-hull Sea Fighter (FSF-1), using a three-dimensional (3D), stereo-optic imaging system. The data obtained were processed using an image matching algorithm resulting in 3D video sequences of the incoming wave field at forward speeds of 16?40 kt in head seas at sea state 4. Six wave slamming events were captured, characterized, and compared to the average wave field properties. It was found that the salient properties of the individual waves that resulted in ship slamming occurred in groups of two or more, were approximately 30% larger than the significant wave heights during the ?2-min period encompassing the slamming events, and had wave slopes at least 2 times that of the preceding wave slope. Additionally, wave slamming corresponded to large ship pitching motions resulting from the incident waveforms.