Comparative study of the effects of length on the resistance of a vessel

In this study, a comparative analysis of the effects of vessel length on hydrodynamic resistance was performed. The research addressed the problem of optimizing hull length to reduce resistance, given its direct impact on fuel efficiency and emissions. Unlike previous studies focused on limited length ranges or specific hull types, this work systematically compared four Wigley hulls (125m, 350m, 370m, 390m) under identical saltwater conditions at 14.6 knots, using both Holtrop-Mennen and CFD (ANSYS Fluent) methods. Results showed total resistance increased with length: from 127.8 kN at 125m to 384.1 kN at 390m—a 188% increase. Frictional resistance rose steadily due to greater wetted surface area (82.1 kN to 360.2 kN), while wave-making resistance decreased from 48.4 kN to 30.5 kN as Froude number reduced. CFD results closely matched empirical predictions, with differences under 2.5%. The study concludes that frictional resistance dominates in longer vessels, outweighing wave resistance benefits. These findings provide critical insights for naval architects to balance length with other design parameters, enabling more energy-efficient vessel designs and supporting maritime sustainability goals. Recommendations include further research on different hull forms and scale effects.