Taking off from water by ground effect craft requires so much power than cruising in ground effect. The difference in the power requirement creates inefficiency in the engine. To reduce the power difference, Mr Hanno Fischer sponsored by the German Ministry for R & D (BMB+F) invented the Hoverwing technology.
The idea is to have air cushion underneath the craft as shown in the presentation below. At about to takeoff, a pylon door opens to channel some of propeller stream for inflating the air cushion. The air cushion provides extra lift and reduces water drag. Consequently, the power required for takeoff reduces substantially. Once the craft is cruising and not in touch with the water, the pylon door closes and the air channel retracted. The propeller stream that is used to inflate the air channel is directed backward to provide additional thrust.
For demonstrations of how Hoverwing technology works, please see our power point slide.