To greatly reduce the fluid friction resistance by providing water- repellent finish to a submerged surface of a body, and feeding air to the submerged surface to form an air layer between the submerged surface and water.

The air layer formed on a submerged surface on which water- repellent finish is provided is not easily separated. When air is fed to the surface of a bottom plate 4, the fed air is not easily diffused into water through suction and merging effect of the air captured by fine rugged surfaces, and does not flow away, and flows along the surface of the ship bottom. The air (a) fed to an outer surface of the ship bottom 4 which is the submerged surface by an air pump 3, forms an air layer (b) consisting of bubbles or air layer. Thus, the fluid friction resistance between the body 2 and water can be greatly reduced during the navigation by operating oars 9, and as a result, the navigating speed can be increased.