The Impact of Sweep Angle on Stepped Planing Hull Performance

Abstract

In this study the impact of sweep angle on stepped hull resistance, running attitude, and dynamic stability is investigated for a range of planing speeds from ventilation inception (𝐹𝛻≈2) to high planing speeds (𝐹𝛻≈7) using RANS CFD. Potential performance benefits of the step are isolated for three speeds and two displacements using fixed trim simulations. Differences in running attitude and dynamic stability are investigated using free running simulations at the highest speed for a range of LCG locations. Finally, any differences in ventilation inception and performance at low speeds are investigated using fixed trim and heave simulations. The study shows that swept forward steps do not necessarily ventilate earlier than other step designs but do provide resistance reductions at 𝐹𝛻<5 compared to swept aft and unstepped designs. However, at 𝐹𝛻>5, swept forward steps demonstrate significant resistance increases compared to unswept and swept aft steps. At high speeds, swept aft steps provide improved dynamic stability compared to other step designs without a resistance penalty when compared to unswept steps.