Optimization of stepped planing hull geometry for improved calm-water hydrodynamic performance

Abstract

This study investigates the improvement of hydrodynamic performance for single- and double-stepped planing hulls using an automated optimization framework that integrates semi-empirical analysis and computational fluid dynamics (CFD). The primary objective is to identify step geometries that minimize calm-water resistance and to extract general design trends relevant to high-speed planing craft. For single-stepped hulls, a modified Svahn semi-empirical method was coupled with the SHERPA search algorithm implemented within Siemens HEEDS MDO to enable large-scale parametric optimization studies. For double-stepped hulls, unsteady Reynolds-Averaged Navier–Stokes (RANS) simulations were employed to capture the more complex hydrodynamic interactions between planing surfaces and to provide higher-fidelity predictions of resistance and trim. The design variables investigated include step height, step length, and longitudinal position for the single-step configuration, with additional mid-body and aft-step parameters considered for the double-stepped hull. The optimization results demonstrate significant reductions in hydrodynamic resistance. The single-stepped hull optimization achieves resistance reductions between 2.1% and 35.9% across Froude numbers ranging from 1.1 to 4.0, while the optimized double-stepped hull exhibits a 5.6% resistance reduction at its design speed. Step height is identified as the dominant parameter, primarily governing wetted area and ventilation behavior. Optimal designs balance frictional drag reduction against increases in pressure resistance and trim. The results provide a quantitative foundation for preliminary stepped hull design and demonstrate the effectiveness of combining semi-empirical and CFD-based solvers within an automated optimization framework.

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ORCID for Tahsin Tezdogan: orcid.org/0000-0002-7032-3038

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