On the Damping of Pitch and Heave

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The determination of pitch and heave damping due to surface-wave propagation is considered, based on a three-dimensional analysis. It is assumed that the pitch and heave motions are sinusoidal and of small amplitude, the ship is moving with small constant forward velocity, the resulting flow is inviscid and irrotational, and that the ship may be represented by a distribution of pulsating sources and sinks. Integral expressions are derived for the four damping coefficients in the equations of motion. Approximate calculations are made for the Series 60 block coefficient 0.60 model at zero speed and these are compared with the two-dimensional calculations.