Ship Maneuvering in Deep and Confined Waters 



0,6 



O.S 



0,i ' 



.0,3 



.0,2 



0.1 







Hull length L 



I I I I t 1 1 



I I I I I I I 



10 



20 



50 



100 



200 m 



Fig. 20. Scale effects on wake factor w as integrated by propeller 

 in model and full scale. 



effective wake factors above 0.38. 



In Fig. 21 the control moment derivative N" for a 98 000 

 tdw tanker is presented as a function of forward speed u and shaft 

 speed n, for a 1:70 scale model as well as for the prototype. 

 (Extrapolation to slowly reversed propeller is shown dotted.) In 

 particular it is seen from the diagram that the turning moment from 

 the rudder at self propulsion point of ship is only some 60 per cent 

 of the model test value. 



During a maneuver the effective change of angle of attack 

 of the rudder is a function of nominal helm deflection 6, drift v, 

 and yaw rate r, and change of screw loading. Again accepting this 

 quasi- stationary model it is 



6. = 



^-(^v^^k.^) 



(7.4) 



859 



