Catamaran resistance is very complex compared to monohull resistance, so it is particularly worthy of research. The below-water-level hull form influences the fluid flow characteristics around the ship, which either increases or decreases the total resistance. This study focuses on developing a new hull form by using the Lackenby Method to modify an existing hull form in such a way that reduces the total resistance. The total resistance was calculated using computational fluid dynamics, since the Navier-Stokes equation is built into the Tdyn software. The research results show that hull form changes can in fact decrease or increase the ship’s total resistance. The best new hull form was chosen for its value of least total resistance.