In this study, a nonlinear optimization method, which is coupled with either a panel method or a vortex lattice method, is used to design open propellers in uniform, circumferentially averaged or non-uniform inflow. A B-spline geometry with 4 × 4 control points is used to ensure that the propeller blade is accurately defined with fewer parameters. The optimization objective is to maximize the efficiency of the propeller while satisfying the given propeller thrust, and different cavity area or pressure constraints are applied. The influence of those constraints are studied, and propeller geometries are designed in different cases. The optimal efficiency as a function of the thrust coefficients are compared with those from other references, and the optimal circulations from this method are compared with those predicted from the lifting line optimization theory. It is shown that this method satisfies the optimization objectives and can be used in the practice of designing cavitating propellers.