Engineering Design of Stepped Hull for Planing Vessels Using CFD-Based Evaluation

The growing demand for high-speed marine transportation requires continuous improvement in ship design to achieve higher hydrodynamic efficiency. From an engineering design perspective, hull form modification is a key approach to optimizing the performance of planing vessels, particularly through the implementation of stepped hull configurations. This study aims to investigate the effects of step geometry and step position on the resistance and trim characteristics of a planing hull based on Taunton et al.’s Model C, with the objective of improving vessel efficiency. The design methodology integrates hull geometry modification, parametric variation in step position and step height, and numerical performance assessment. In this research, the governing equations are solved using the Reynolds-Averaged Navier–Stokes (RANS) framework with the Finite Volume Method (FVM) as the discretization technique. The turbulence model used is k-ω SST, while the interaction between water and air phases is represented using the Volume of Fluid (VOF) method. From a design performance perspective, the results demonstrate that stepped hull geometry significantly influences resistance and trim characteristics. The optimal design configurations achieved a resistance reduction of up to 17.93% and a trim of 1.53° was achieved with a stepped position of 430 mm from the transom and a stepped height of 25 mm (Model A3) at Fr 2.28. Meanwhile, a resistance reduction of 15.49% and a trim of 1.46° were observed for a stepped position of 860 mm from the transom and a stepped height of 25 mm (Model B3) at Fr 2.72. These findings highlight the importance of step geometry and placement as key design variables in improving planing hull performance. This study demonstrates that CFD-based evaluation can effectively support engineering design decisions for stepped hull optimization, providing a systematic approach for improving hydrodynamic efficiency in high-speed vessel design.