Planing hulls were recognized for several decades as high-speed, high-performance marine vessels. In this research, the effect of keel curvature variations on hydrodynamic loads and the phenomenon of porpoising has been investigated for a type of planing hull. This study aims to optimize hydrodynamic performance and reduce dynamic instabilities. In this work, the geometry of the Fridsma planing hull was first modeled using SolidWorks software, and then simulated using STAR-CCM+. To examine the effect of keel curvature variations, numerical methods and experimental data were used for validation of the results. Furthermore, by designing and analyzing a sample of a Wing-In-Ground (WIG) effect craft hull with a single step, and applying changes in the keel curvature, the impact of these variations on hydrodynamic loads in turbulent flow conditions in calm water has been studied. For the purpose of flow simulation, the fluid is assumed to be incompressible, and for dynamic analysis of the vessel, its motion in the degrees of freedom of heave and pitch has been considered. The SIMPLE algorithm is used to couple the momentum and continuity equations. Turbulent flow modeling has been carried out using the k-ω SST turbulence model, and to simulate the interface between the two phases, the Volume of Fluid (VOF) method is applied. The results of this study show that variations in keel curvature can significantly affect the dynamic behavior and overall performance of the vessel. It was also observed that keel curvature changes alone cannot be considered a sufficient factor for optimal vessel design, and parameters such as keel curvature, vessel speed, and motion phase must be taken into account. Moreover, at a speed of 12 m/s with a keel curvature of n=2.5, the porpoising phenomenon was observed. In the case of the WIG craft, it was also found that by applying changes in keel curvature and analyzing their effect on hydrodynamic loads in calm water, the optimal keel curvature an