Hull form optimisation to minimise the total resistance and dynamic responses of small fishing vessels
Muhammad Iqbal, Momchil Terziev, Tahsin Tezdogan, Atilla İncecik
Abstract
This paper presents a novel approach to ship hull form optimisation, aimed at minimising total resistance while simultaneously enhancing the seakeeping performance of a fishing vessel. When conducting optimisation process in minimising resistance, the method employs the minimisation of the y-axis radius of gyration (Ry) by optimising the longitudinal centre of gravity (LCG) and vertical centre of gravity (KG). The influence of altering LCG and KG on Ry, total resistance, and seakeeping is explored. Reducing Ry enhances seakeeping performance, lower added resistance, resulting in a reduced mean total resistance in waves. This finding demonstrates that it is possible to reduce resistance and improve seakeeping performance simultaneously without the need for multi-objective optimisation to balance the two. By employing the method outlined in this paper, seakeeping performance can be enhanced alongside resistance optimisation in a single process. The optimal hull form can reduce root mean square (RMS) vertical acceleration, RMS pitch motion, and added resistance on average by 1.79%, 1.51%, and 6.48%, respectively. In addition, the mean total resistance in waves for the optimised hull form was reduced by up to 4.15% compared to the initial hull form. This method offers a streamlined solution to achieving multiple performance objectives concurrently. • The optimisation of the hull form of a fishing vessel to minimise total resistance and dynamic performance was conducted simultaneously, without the need for multiobjective optimisation. • The radius of gyration about the Y-axis (Ry), a novel objective function in seakeeping optimisation, is introduced. This function indirectly predicts seakeeping performance, thereby streamlining the optimisation process. • Direct CFD simulations for seakeeping performance were not conducted during the optimisation process. Instead, these simulations were used to compare the initial and optimal hull forms, making the optimisation process faster. • Both resistance in calm water and waves, as well as the dynamic performance of the optimal hull form, can be reduced compared to the original design.