| Z.Ali and G. Bognár Institute of Machine and Product Design, Faculty of Mechanical Engineering and Informatics, University of Miskolc, 3515-Egyetemváros, Miskolc, Hungary Abstract: Hull surface roughness, resulting from fouling or coating degradation, significantly increases hydrodynamic resistance, leading to higher fuel consumption and greenhouse gas emissions. This study investigates the impact of uniform full‐hull roughness on the hydrodynamic performance of the KVLCC2 tanker through full‐scale Computational Fluid Dynamics (CFD) simulations, complemented by predictions from the empirical Katsui Roughness Correlation. The analysis covers design and slow operating speeds, with roughness heights ranging from 0 to 5000 μm. CFD results quantify the increase in total resistance, effective power, and fuel demand, revealing frictional resistance as the dominant contributor at low Froude numbers. Comparisons with Katsui’s predictions show consistent underestimation of resistance and power penalties, with discrepancies exceeding 50% for severe roughness. These findings indicate that sole reliance on Katsui may lead to significant underprediction of operational costs. Integrating CFD with empirical methods provides a more robust basis for performance assessment, supporting compliance with energy‐efficiency regulations such as EEDI and SEEMP. © European Society of Computational Methods in Sciences and Engineering Keywords: Hull roughness, CFD, Katsui correlation, KVLCC2, frictional resistance, effective power, fuel consumption. Mathematics Subject Classification: 76D07, 76M25, 65N30 PACS: 47.11.-j, 47.85.Dh, 47.55.-t |