According to the slender ship theory, the wave-making resistance of ships is definitely determined by the sectional are a curve alone as far as the so-called, end effect' terms are neglected. As a preliminary verification to this conclusion, a set of three symmetrical models with C _B=0.55 ( L/T =20) are tank-tested. From the presently obtained results a tentative conclusion may be drawn that the designed waterline form atF.P.8¹/₂ affects the wave-making characteristics of ships as seriously as the sectional area curve.