Wings in the vicinity of free surface may produce 30%-over lifts than those in an infinite medium of air. Therefore, airplanes in the proximity of free surface use less fuels. This is the well-known WIG effect. A WIG ship is such that it makes use of WIG effect achieving speed up to 100 kn, much faster than the fastest ships in the world. So WIG ships are called The Fourth-Generation Transportation Vehicles. The present project aims to generalize the Prandtle lifting theory in an infinite fluid medium to a theory in the vicinity of free surface with severe sea states and climate factors taken into consideration. The Method provides effective tool for design and research of WIG ships.