To improve propelling force and stability by providing multiple rotary spokes having variable-pitch wings on drive wheels driven by the drive shaft of a drive engine.

Chains 14, 15 driving drive wheels 4, 5 are hooked on the drive shaft 3 of an engine 2. The drive wheels 4, 5 are provided with vanes 6 of rotary wings, pitch changing rods 8 changing the pitches of the vanes 6, and multiple rotary spokes 7 radially having the wanes 6 via rotary shafts 9. The drive wheels 4, 5 are fixed to a body 12 via support shafts 10 vertically adjustable in height. When this motor scooter l is to be accelerated, the pitch changing rods 8 are shortened, the vanes 6 are set to the angle for paddling the water surface 30. When the motor scooter 1 is to be decelerated, the pitch changing rods 8 are extended, the vanes 6 enter the water at the angle for resisting the water surface 30, and these actions are adjusted by a computer. A ship- shaped buoyancy device having gaps through which the vanes 6 and rotary spokes 7 pass is provided for stability on the sea surface 30.