Fig.4.6 and Fig.4.7 show the results for deviated maximum lateral distance from the original course with function of SP12/L1 for the case of overtaken and overtaking PCC vessel under the condition of U2/U1 = 1.2. In this case, the separation between two ships, SP12 was chosen to be 0.3 to 0.7 times of L1 and L2/L1 was taken as 1.0 in h/d=1.2. Also, in these and all following calculations, the wind velocity VW was taken as 15m/s. From these figures, an overtaking vessel with ranges of 10 degrees in maximum rudder angle can be manoeuvred safely without deviating from the original paths under the condition of SP12/L1 = 0.4. But, the deviation for the case of overtaken vessel with ranges of 10 degrees in maximum rudder angle under the condition of v = 90° is comparatively larger from its intended course. Besides, an overtaking and overtaken vessel with maximum rudder angle of 5° under the condition of v = 90° cannot navigate regardless of SP12/L1 because of ship collision due to insufficient rudder force corresponding to the rudder angle.

　

 Fig.4.8 and Fig.4.9 show the results for deviated maximum lateral distance from the original course with function of SP12/L1 for the case of overtaken and overtaking PCC vessel under the condition of U2/U1 = 1.5. From these figures, it indicated that the results for two ships represent almost qualitatively same tendency, compared to the case of U2/U1 = 1.2. In addition, the lateral distance between two ships and maximum rudder angle are necessarily required for the velocity ratio of 1.2, compared to the case of 1.5 because it is mainly attributed to lengthening the mutual effects on their relative position between two ships. Meanwhile, regardless of wind velocity and direction, an overtaken and overtaking vessel can be manoeuvred safely without deviating from the original paths under the two conditions; the lateral separation between two vessels is approximately kept at 0.5 times of ship 1 and the maximum rudder angle should be smaller than 15 degrees.