The surface force, which is a cause of ship hull vibration, is due to oscillating pressure on the hull induced by a propeller. In the present paper analytical investigation has been performed into characteristics of oscillating pressure on a horizontal plane fixed in the space above a propeller. At first the general formulation of the pressure field around a propeller has been made as the general solution of the Poisson equation. The well-known expression by loading and thickness effects has been deduced by linearized approximation of the solution. The relation between the integral equation of Ishida's theory and the general solution has been explained. It has been pointed out that the relative position of the calculation point to back or face sides of propeller blades is an important factor to control the characteristics of the pressure distribution. Numerical examples have been made for a uniform flow and two nonuniform harmonic wake flows, cos 2θ and cos 5θ wake distributions. The calculated results for a five-bladed propeller have shown the normal distribution of oscillating pressure in case of a uniform flow and cos 2θ wake flow but an abnormal distribution in case of cos 5θ wake flow. Such calculations have been in good agreement with the measured results by experiments in the towing tank.

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