The wake measurements and the propulsion tests of a model ship are carried out to study the influence of the hull on the propeller slipstream and the effect of the rudder on the propulsive performance. The experiments and the theoretical considerations, show the following results: (1) The rotational flow behind the propeller in the hull wake is similar to the flow behind the propeller operating in the open water with the same advance speed and number of revolutions. The interaction between the hull and the propeller, however, makes the axial flow distribution in the hull wake different from in the open water condition. (2) The amount of the rotational energy in the propeller slipstream behind the hull and the propeller agrees relatively well with the amount in the open water condition. (3) The delivered horse power of the hull with the rudder is less than without the rudder. The decrease of the power agrees generally well with the difference between the decrease of the kinetic energy in the propeller slipstream and the increase of the energy dissipation generating mainly in the boundary layer on the rudder.
