A forced oscillation method same as was used in the case of pitching was employed. The effects : of ship forms upon additional mass and damping force are discussed about the values corresponding to the ship's natural frequency.
It was found that the ratio additional mass to ship's own mass increases when C_b and B/L increases, that damping coefficent decreases when C_b, increases and increases when B/L increases. Charts of added mass coefficent and damping coefficent same as for pitching motion are also proposed in this paper.