Seakeeping time domain simulations for surf-riding/broaching: investigations toward a direct stability assessment

Seakeeping time domain simulations are carried out to capture the likelihood of a surf-riding and/or broaching event, with the aim to gain a further insight into the ship performance in stern quartering seas. The applied numerical tool, named PANSHIP, is a 6-DoFs time domain seakeeping software based on panel method, combined with semi empirical viscous models. The investigated ships are two yacht vessels and a patrol boat. Calculations are also carried out with a tool implementing the IMO second level vulnerability criterion for surf-riding/broaching. Similarities, differences and critical issues of both approaches are discussed, as a first step in the perspective of a comprehensive application of the IMO Second Generation Intact Stability criteria, inclusive of the so-called “Direct Stability Assessment”.