Forces in pure-yaw motion;

 Fig. 5 shows another expression of the quasi-stationary hydrodynamic forces (symbol:・) exerted in a harmonic captive test of pure-yaw motion (|r'|≦40 see Table 2). Fig. 5 also contains the stationary hydrodynamic forces (symbol:○) exerted in a stationary circular test of pure-turn towing motion (|r'|≦1) [4] for the comparison and validation of the quasi-stationary hydrodynamic forces. Fig. 5 indicates that the quasi-stationary hydrodynamic forces of the pure-yaw test do not agree well with the stationary hydrodynamic forces of the pure-turn towing test, because of the small hydrodynamic and large inertia forces in measured forces YE.

　

 Forces in combined motion;

 Fig. 6(a) shows the another expression of quasi-stationary hydrodynamic forces (symbol:・) exerted in a harmonic captive test of combined motion (|β|≦45°,|r'|≦0.31 see Table 2), while comparing the forces with the stationary hydrodynamic forces (symbol:○) in the oblique towing test (β≦90°). The resultant forces affected by the yaw rate in a combined motion shows the locus making a loop in Fig. 6(a). Fig. 6(a) may indicate that the quasi-stationary hydrodynamic forces in combined motion agree well with the stationary hydrodynamic forces in the oblique towing test, if the correction due to yaw rate is performed to the forces in combined motion.