Session: 15-07-01 Ship Manoeuvring, Resistance and Propulsion

Submission Number: 181118

Optimization of Stepped Planing Hull Geometry for Improved Calm-Water Hydrodynamic Performance 

This study examines how the hydrodynamic performance of single and double-stepped planing hulls can be improved through an automated optimisation framework that integrates semi-empirical and computational fluid dynamics (CFD) analysis. The objective was to identify step configurations that minimise calm-water resistance and reveal general design trends applicable to high-speed planing craft.

For single-stepped hulls, a Modified Svahn semi-empirical model was coupled with the SHERPA search algorithm in Siemens HEEDS MDO to perform large-scale parametric studies. For double-stepped hulls, unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations provided high-fidelity resistance and trim data over comparable design spaces. The main parameters included step height, step length, and longitudinal position for the single-step case, with additional mid-body and aft-step parameters for the double-step configuration.

The optimisation identified substantial improvements in resistance performance. Single-stepped hulls achieved reductions between 2.1 % and 35.9 % across Froude numbers 1.1–4.0, while the optimised double-stepped hull achieved a 5.6 % reduction at its design speed. Step height was found to be the most influential variable, directly affecting ventilation length and wetted-area reduction. Optimal performance resulted from balancing the competing effects of reduced frictional drag and increased pressure resistance.

For double-stepped hulls, interactions between the four key design parameters produced several near-optimal configurations. The mid-body aspect ratio and wetting behaviour strongly influenced total resistance and longitudinal stability, highlighting the need to evaluate step geometry globally rather than in isolation. Across all cases, drag reduction was governed by minimising wetted area while avoiding excessive trim or porpoising.

The findings establish a quantitative basis for the preliminary design of stepped planing hulls and demonstrate the effectiveness of coupling semi-empirical and CFD solvers with automated optimisation algorithms. The proposed framework enables rapid exploration of complex design spaces, accelerating the development of efficient high-speed vessels and providing a foundation for future extensions to seakeeping and manoeuvring optimisation.

Presenting Author: Tahsin Tezdogan University of Southampton

Presenting Author Biography: Prof. Tahsin Tezdogan is currently a Professor of Marine Hydrodynamics in the Department of Civil, Maritime and Environmental Engineering at the University of Southampton.

Prof. Tahsin Tezdogan received his PhD in 2015 from the University of Strathclyde, in the Department of Naval Architecture, Ocean and Marine Engineering. His doctoral thesis was entitled "Potential Flow and CFD-Based Hydrodynamic Analyses of Mono- and Multi-Hull Vessels."

Prof. Tezdogan has a broad range of research interests, including CFD simulations of ship motions and resistance, the added resistance of ships in waves, and the performance of vessels in channels and canals. He has contributed to several internationally collaborative projects funded by the EU, the Newton Fund, and the Global Challenges Research Fund. More recently, he has led Clean Maritime Demonstration Competition (CMDC) projects, including Supercharging Wind Propulsion (CMDC4), GenDSOM: Leveraging Generative AI for Next-Generation Vessel Design and Manufacturing, and Streamlining High Fidelity Simulation for Wind Assisted Ship Development (CMDC6), advancing sustainable and zero-carbon shipping technologies.

Authors:

Angus Gray-Stephens University of Strathclyde
Tahsin Tezdogan University of Southampton