Gadd 



of Pbest ^^ given by Eq. (10), the latter may not be too much of an overestimate 

 at the low Froude-number end. At the other extreme, it cannot be expected to 

 apply for speed-to-length ratios much larger than for the frigate results used in 

 its derivation; hence we restrict N, given by Eq. (9), to values less than 2. 



Figure 3 shows curves of P^est' given by Eq. (10), as a function of dis- 

 placement A for various speeds V, It also shows the corresponding curves of 

 P . , given by Eq. (6). Even with very sophisticated design, ship powers are 

 never likely to come down as low as P^in, but the difference P^est ~ Pmin never- 

 theless gives some measure of the improvement over the best current designs 

 which might conceivably be achievable. Most of the ship powers given in Table 

 3 lie above the P^est curves, in some cases a great deal above, as is only to be 

 expected, since the curves of Fig. 3 are (subject to the possible reservation 



100. coo 



90, 000 



so, ooo 

 70, ooo 



£0. 000 

 50,000 



40,000 



30,000 



10,000 

 9 ooo 

 8 ooo 



7,000 



eooo 

 s.ooo 



500 1000 2000 



SOOO 10000 20000 



100000 200000 



i,ooo 



900 

 80O 

 700 



eoo 

 soo 



400 



50O ooo 2O00 5000 IQOOO 20.000 50,000 lOCPOOO 200000 



A , tons 



Fig. 3 - Curves of horsepower versus dis- 

 placement for various speeds V (knots) 



714 



