When cylinders of Lewis Form sections heave and pitch on the free surface, their damping force and the added mass were exactly calculated by Ursell's Method. And many figures in this report show the results of the calculation. Then the reporter calculated, applying the results of the above-mentioned calculation and by Strip Method, the damping force and the added mass of the two ships, which were respectively put to test by Golovato and Gerritsuma. The added mass and the added moment of inertia which the reporter gained by Strip Method showed good coincidence with the results of Golovato's and Gerritsuma's experiments. To get better estimation on the damping force by Strip Method, it is necessary to calculate more closely the three dimensional effect, non-linear effect, etc. As to the added mass the three dimensional correction could be negligible except for small ξ₁^*.