Abstract: This invention relates to a boat, the bottom of which is provided with a plurality of downwardly opening channels intended to receive air during the forward movement of the boat in order to produce a reduction of the friction between the water and the bottom surface. In order to make the air inflow into the channels easier these are, regarded from above and from below respectively, extending along their whole extension mainly parallel to the bottom line of the boat in the direction astern from places at the stem of the boat above the water surface to places under the water surface.