Hydrodynamic characteristics of an ILCA6 sailing dinghy in calm water and head waves

Abstract The ILCA6 (formerly Laser Radial) sailing dinghy frequently encounters wave conditions during training and competition, where wave-induced resistance and ship motions can significantly influence sailing performance. However, systematic investigations of the hydrodynamic characteristics of ILCA6 dinghies under regular head wave conditions over a wide range of sailing speeds and wavelengths remain limited. In this study, computational fluid dynamics (CFD) simulations were conducted to investigate the calm water resistance and hydrodynamic responses of an ILCA6 sailing dinghy in regular head waves. The total resistance, added wave resistance, heave, pitch, and their corresponding response amplitude operators (RAOs) were analyzed under sailing speeds ranging from 2 to 6 m/s and wavelength-to-waterline length ratios from 0.5 to 2.0. The numerical method was first validated against available experimental data, showing good agreement in the prediction of added wave resistance and motion responses. The results indicate that the total resistance increases with ship speed under both calm water and wave conditions, while the added wave resistance exhibits a pronounced dependence on both wavelength and sailing speed. The heave and pitch responses generally increase with wavelength, with more significant variations occurring when the wavelength approaches or exceeds the ship waterline length. By systematically evaluating the resistance, added resistance, and longitudinal seakeeping responses over representative operating conditions, this study provides a comprehensive understanding of the wave-induced hydrodynamic behavior of the ILCA6 sailing dinghy. The findings provide useful hydrodynamic references for sailing performance assessment and future performance optimization of racing dinghies.