41 



Low prlsmatics (t> are a necessary condition for good resistance qual- 

 ities below the first hump, F < 0.32. Normally considerations of resistance 

 are so decisive for vessels operated within the range 0.32 > F > 0.25 that 

 only small ^ values should be used. Grave mistakes have been committed when 

 designing liners with rather high prisraatics, although the basic facts could 

 have been easily ascertained from Taylor's Standard Series. For ship types 

 run at P < 0.25, it may be more advantageous to compromise between resistance 

 and carrying capacity, since the absolute value of the wave resistance de- 

 creases. Thus, moderate prismatics become a reasonable solution. 



At the same time, ship lines with vanishing curvature K gain in im- 

 portance, as may be guessed from Figures 26 to 28 representing S(y) curves for 

 ^ and t = const corresponding to different equations. The family (3,4,6) ap- 

 pears to, be useful over a certain range; with increasing 4> and reduced speed 

 ratios, ship lines corresponding to higher degree polynomials become advan- 

 tageous. The influence of K = or, more generally, of a parallel middle body 

 expressed by an increase of degree in a polynomial on the resistance is oppo- 

 site to the increase of <f> and t: The humps in the function S(r) are shifted 

 to the right (smaller F). Our analysis shows that Taylor's Standard forms 

 ^=0.6 and = 0.64 are quite successful, but not outstanding within their 

 useful speed ranges; it is possible to obtain better results when bulbs are 

 fitted to some of the good normal forms here discussed (Figures 19^, 20, 26, 

 27). 



Figure 17 - Ship Lines - Basic Family (2,4,6; 0,t) t = 1 



