Behavior of Unusual Ship Forms 



to study the deep submergence frictional characteristics in order to determine 

 whether there indeed exists an optimum form in the design Froude number 

 range. Figure 4 indicates for such bodies the specific horsepower (EHP per 

 ton of displacement) as a function of speed, fineness ratio and body length. 

 Since for each set of fineness ratio curves the velocity is constant and the 

 abcissa used is body length, it is possible to associate a Froude number with 

 that velocity and body length. Therefore, a Froude number scale is superim- 

 posed on the abcissa of the figure. We see from Fig. 4 that there does indeed 

 exist for, say, a 3,000 ton vessel an optimum fineness ratio of 5. This was used 

 in the design of the Hydrofoil Semi-Submarine. 



We will dwell a little further on the Hydrofoil Semi -Submarine in order to 

 acquire a proper interpretation of the information to be presented subsequently 

 for comparison with the other ships. A substantial part of the tests performed 



_ L/D=IO 



BODY LENGTH L, FT 

 190 170 160 



1.2 I .3 



FROUDE NUMBER 



45 KNOTS- 



A = 2000 TONS 



A=3000 TONS 



BODY LENGTH L , FT. 

 210 190 170 



0.8 



0.9 



1.0 

 FROUDE NUMBER 



Fig. 4 - Specific horsepower (strearaline bodies of 

 revolution at deep submergence) 



721 



