This paper presents a comprehensive methodology for studying the speed and power performance of a vessel under varying operational conditions, with particular emphasis on the impact of biofouling condition on the hull and propeller surfaces. Biofouling condition on the ship’s surfaces is modeled as surface roughness, and its impact on power performance is incorporated using Schultz’s approach for hull resistance and a model examined by ITTC for propeller open water characteristics. Additionally, the influence of hull surface condition on wake fraction is analyzed through CFD simulation results. The methodology is applied to the assessment of the speed and power performance of a VLCC at typical service speeds. This approach aims to facilitate the rapid estimation of the life-cycle fuel consumption of a ship.