1.0 



0.9 



0.8 



0.7 



-===:• 0.56 a 0.562 

 /Ubp 



®'l.l90.7ijy0.50 



\ \ 1 \ 



Service Speed (K) ' 1.190 (Alexander) 



Trial Speed (K) • 1.332 (Alexander) 



Sustained Speed (R) = 1.335 (Trooet)" 



Trial Speed ® • l.4l5(Trootf) 



4.0 3.0 2.0 1.0 23 10 2.0 3.0 



A LCB From SI "s % LBP F 



Figure 30 - Cross Curves of © on LCB. Cu = 0.80 



4.0 



values of @ corresponding to the Alexander and Troost speeds set out in Table 9. The 

 locus of the LCB position for minimum resistance is indicated on each figure. Table 26 

 summarizes the data, from all five figures. 



The optimum LCB locations and the corresponding minimum (C) values are given in 

 Figure 31. This shows how, for a given block coefficient, the optimum LCB location moves 

 aft as the desired speed is increased. When the block coefficient and speed are known, this 

 figure will give the optimum LCB position and the corresponding minimum @ value which 

 will result if the lines of the ship conform with those of the Series 60 contours. Thus for a 

 block coefficient of 0.65 and a speed correspcmding to ® = 2.1, entering Figure 31 on the 

 (5) scale, we find the best position of LCB is 1.45 percent LBP aft of 25, the correspond- 



ing minimum (c) 400-ft value being 0.73 and 



V 



= 0.82. This chart, in fact, summarizes 



'BP 



the conclusions to be drawn from the resistance data and should be of considerable use to 

 designers in all cases where the lines and proportions are not too different from those of 

 the series. 



One point of considerable interest which arises from these data is the remarkable 

 constancy of the minimum (C) value at the sustained sea speed as defined by Troost. These 

 speeds are shown in Figure 31; for block coefficients varying from 0.60 to 0.80, tiie minimum 

 (£) 400-ft values at 0.05 intervals in coefficient are respectively, 0.735, 0.720, 0.730, 0.740, 

 and 0.740. 



VI-13 



