An Integrated Numerical and Bollard Pull Evaluation Approach for Early‐Stage Resistance and Thrust Assessment of a Small Craft

ABSTRACT Early‐stage hydrodynamic assessment of slender multihull vessels is challenged by limited geometric maturity, uncertain propulsion integration, and strong sensitivity to operating conditions. Under such constraints, reliance on a single analytical or numerical method may lead to misleading design decisions due to oversimplification or premature confidence in preliminary predictions. This study proposes an integrated decision‐support evaluation that combines slender body theory, Computational Fluid Dynamics (CFD)‐based numerical analysis, and experimental bollard pull testing to evaluate resistance and thrust characteristics during the early design stage. Slender body theory is employed for rapid trend‐based resistance estimation, while CFD simulations resolve nonlinear viscous and free‐surface effects that emerge at higher Froude numbers. Experimental bollard pull tests provide a physically measurable reference for propulsion capability during early‐stage assessment. The workflow is applied to a slender catamaran hull across a range of operating speeds to examine consistency and divergence among methods. The results show that the three approaches provide complementary insight into resistance and propulsion feasibility, enabling the identification of feasible operating regions and propulsion margins during preliminary design. The novelty of the proposed approach lies not in the individual methods themselves, but in their integration into a thrust–drag envelope framework that directly connects resistance requirements with experimentally measured static thrust constraints. This framework provides a practical basis for uncertainty‐informed feasibility assessment and early‐stage design decision‐making.