There is few theoretical study on the variation of wetted length or area of a ship gliding on water surface in spite of its practical importance. To improve this defect of theory, the present report proposes a linear solution representing the elongation of wetted length at first. This linear approximation tells us fairly well the variation of wetted length in two-dimensional case. The foregoing theory considers only induced velocity but not induced surface elevation, so that profiles of the ship obtained may differs from the ones assumed to be. Thence, the equation representing the surface elevation is introduced, calculated in some cases of simple pressure distribution and found their interesting character. Finally, an example to calculate the variation of wetted area is shown by making use of a two dimensional linear solution representing the elongation of wetted length.
