The performance evaluation of ships is essential to prevent maritime accidents; however, compared to that of large commercial vessels, the evaluation of fishing vessels remains insufficient. Specifically, for fishing vessels under 5 tons, no evaluation is conducted during the design stage. Unlike commercial ships, the maneuverability of fishing vessels is often neglected during the design process or assessed using empirical formulas. For small fishing vessels, significant variations in weight and center of gravity occur depending on loading conditions. Therefore, even if maneuverability is evaluated through sea trials after design, these trials may not fully reflect actual operating conditions. Consequently, the performance evaluation of small fishing vessels should be distinguished according to loading conditions. This study focuses on a 4.99-ton standard fishing vessel, utilizing the K-SHIP program from the Korea Maritime Transportation Safety Authority to evaluate weight and center of gravity under different loading conditions, and subsequently analyze the turning performance of the vessel. Uncertainty in the CFD simulations was validated using the GCI method, whereas the simulation results were verified for accuracy using sea trial data. The findings indicate that the turning performance of the vessel at the design speed under the ‘Full Loading DEP’ condition is representative of its maneuvering performance at that speed. Moreover, the simulation results across various speeds highlight the importance of selecting operating speeds that consider the turning performance of small fishing vessels.