This paper examines the effect of the stern wedge length and height on the drag and trim of a chine-planing hull in calm water. To this end, fluid flow was simulated by Star-CCM+ software by applying an overset mesh and k-ε turbulent model. The finite volume method was used to discretize the fluid domain, and the fluid volume was utilized to capture the generated free surface. The considered model is a prismatic planing hull with a deadrise angle of 24°, a mass of 86 kg, a length (L) of 2.64 m, and a beam (B) of 0.55 m. For validation, the numerical results of drag and trim were compared against experimental data, which displayed good compliance. Subsequently, the hydrodynamic performance of the planing hull was investigated, and the wedge effect was assessed. The stern wedge was located at the bottom and near the aft perpendicular to the hull to facilitate a moderate distribution. Various wedge lengths of 0.2B, 0.5B, and B at two different heights of 5 mm and 10 mm were examined to assess the hydrodynamic performance of the hull at various speeds. The trim angle, resistance, water surface elevation, porpoising, roster tail, and the stern and bow were computed and analyzed. Based on the numerical results, it was concluded that when the wedge length increased, the drag and trim were reduced. It was also concluded that the best wedge for a vessel with desirable wake generation is one with a length of 0.2B and a height of 5 mm.