With three ship models having C_B=0.60, 0.70, 0.80 of Series 60 parent forms, and five ship models of high speed ship forms, pitch, heave and resistance increase in regular head waves are obtained from experiments and theoretical computations. From the results of the experiments and calculations, the influences of block coefficients, beam-draft ratios and displacement-length ratios on pitch, heave and resistance increase in regular waves are investigated. It is shown that the larger the block coefficient, the beam-draft ratio or the displacement-length ratio the larger the resistance increase. Since damping coefficients of ships of large beam-draft ratios are larger than those of ships of small beam-draft ratios, it is also concluded that the pitch and heave of the former are smaller than those of the latter.
