the water surface 78 as indicated by the dotted lines in fig1 when the sailboat 10 reaches planing speed a substantial portion of the bottom surface 34 of each hull member 12 is lifted above the water surface 78 as illustrated by fig1 the forebottom surface 40b is out of the water except for the planing area 54 most or all of the midbottom surface 42b is lifted above the water surface 78 at least part of the planing area 55 of the aftbottom surface 44b remains in contact with the water surface 78 rather than having a wetted surface which extends for the length of the hull each hull member 12 has separate wetted surfaces at the first planing area 54 and at the second planing area 55 this reduction of wetted surface under planing conditions enables the sailboat 10 to have increased speed over conventional designs the center of gravity of each hull member 12 is between the first planing area 54 and the second planing area 55 near the power thrust from the mast and sails this construction forces the first and second planing areas 54 and 55 to maintain contact with the water surface 78 under all planing conditions thus the design of the hull members 12 does not sacrifice stability in order to increase speed by keeping the.