Improving seakeeping performance of fishing boats by minimising radius of gyration

Since the mortality rate of fishing at sea is the highest compared to other occupations in the world, improving the seakeeping performance is essential to enhance the safety of fishing vessels. One approach is to conduct seakeeping optimisation, which typically involves multiple objective functions. This study simplifies the objective function in seakeeping optimisation by using a single objective function: the Radius of Gyration in the Y direction (Ry), while varying the Longitudinal Centre of Gravity (LCG) and the Vertical Centre of Gravity (KG) positions as design variables. A Central Composite Design was employed to generate sample data, enabling the construction of a mathematical model and the identification of the optimal solution using Response Surface Methodology. The initial and optimal results, based on CFD simulation, were compared. The findings reveal that the optimum design variables in Ry, can enhance seakeeping at certain wavelength ratios, resulting in a lower RAO value compared to the initial condition. Furthermore, the influence of the design variables on total resistance (RT) was investigated. The results demonstrate that the seakeeping optimum has no significant impact on total resistance, as the difference with the optimum design for RT and the initial condition is very low, predicted to be no more than 0.5%. This discovery suggests that minimising Ry can improve seakeeping without significantly affecting total resistance.