Investigation of Severe Vertical Accelerations of Sailing Yachts in Regular and Irregular Waves

This study presents the development of a 3 DoF mathematical model for the motions of sailing yachts in surge, heave and pitch modes. The model is used for carrying out massive batches of simulated scenarios, in between which the yacht heading, wave length and wave steepness are incrementally varied. Analysis of the results is performed within the scope of identifying severe vertical accelerations causing crew discomfort, as a first step to a criterion towards identifying slamming events. The hydrodynamics utilize the discretization of the hull geometry into flat triangular panels and all wave loads are involved by accounting for the instantaneous wetted surface. Incident wave loads are calculated in real time as the simulation commences, while radiation and diffraction loads are pre-calculated and provided via appropriate interpolation tables. For the sails excitation and within the concept of a yacht sailing upwind, a steady thrust force is assumed and enforced. Results for the case of regular waves prove the capability of the model to identify avoidable parameter areas. Analysis of the irregular waves cases shows interesting statistics on the duration of the events.