In the previous paper, the authors presented a theoretical approach to the self-propulsion test of a full ship, which utilized measured hull resistance and wake data for a model (L_<pp>=8.0m). In this paper, they investigate scale effect on propulsive performance of a full ship which consists of an actual hull form and an infinitely bladed propeller. In computing propulsive performance of the ship of different scale (L_<pp>=4m, 12m, 302m), the total resistance of the ship is obtained based on the three-dimensional extrapolator method using Hughes' line and the nominal wake distribution is obtained by Sasajima's method. Two kinds of skin friction correction (SFC) are mainly selected: zero SFC and SFC based on I.T.T.C. 1957 line (ΔC_F=0.0002). Contraction of the wake due to propeller suction is also approximately considered in the calculation. The frictional part t_f of thrust deduction fraction is assumed to be 0.015. Results are analysed based on the thrust-identity method assuming that the open water propeller characteristics have no scale effect. Following conclusions may be drawn; (i) Scale effect on thrust deduction fraction is generally small and seems to depend on wake, propeller load, hull form etc. (ii) Relative rotative efficiency is larger for a full scale ship than for a model ship. This may be due to large circumferential inequality of wake distribution for a full-scale ship. (iii) Quasi-propulsive coefficient has small scale effect, though propeller efficiency and hull efficiency have considerable scale effects. (iv) The rate of revolutions of the propeller and delivered horse power of a full-scale ship are estimated with good accuracy by considering SFC. (v) By using calculation method described here, the rate of revolutions of the propeller and delivered horse power at speed trials are estimated pretty well.
