Power prediction for WIG crafts is challenging. This is due to the lack of information about its performance data, and hence, there is no simple method for power prediction yet available that can be used in preliminary design stage. In this paper, a method to predict the required power for WIG craft is presented. The authors assume that WIG craft is a prismatic planing hull facilitated with wings and longitudinal stabilizer. The hydrodynamic and aerodynamic characteristics which describe pitching moment, lift, drag, and different centers of each force are represented in a developed mathematical model. An iterative computer program is structured using FORTRAN language. The output of this proposed method gives the logic and acceptable performance of WIG craft compared to related planing hull. An illustrative example is included to determine the required horsepower, running trim and take-off speed.