were Indirectly checked later by fitting equal bulbs to the two models. Further 

 comparative calculations were made for sectional-area curves of Taylor's Stand- 

 ard Series.*' From Figure l4 it follows that Taylor's form for </> = O.56 is 

 very near to the good one (2,4,6; O.56; 1). The associated S(y) and S^(r) 

 curves indicate clearly the excellent resistance properties of Taylor's forms 

 for low and moderate Proude numbers, when ^ = O.52 and O.56. 



Important conclusions can be drawn from these Investigations, which 

 have been anticipated to some extent in our introductory remarks: 



a. Small deviations in form may cause appreciable differences in wave 

 resistance; the "fairness of lines" does not give the slightest indication as 

 to wave-resistance properties. For instance the line (2,3,4; O.56; 1) is 

 "fairer" than (2,4,6; O.56; 1) since it has only one point of inflection. 



b. Every ship form is a unique problem; one must be very cautious in 

 extra- or interpolating resistance properties when the decisive parameters of 

 the problem are not known. 



c. Theory gives powerful, if not thoroughly reliable, means of investi- 

 gating even fine peculiarities of from with respect to their wave-resistance 

 properties. 



d. Changes in wave resistance due to deformations of models (for in- 

 stance of wax models by high temperature) may account in some cases for incon- 

 sistencies in model results, especially in cases where repeated experiments 



do not agree with the original ones. 



In the present case the parameter K proved to be significant as re- 

 gards wave resistance. As an example, the resistance properties of two ship 

 lines were Investigated, which were derived by adding to a given line two 

 polynomials expressed symbolically by (2,3,4,6; 0; 0) and (2,4,6,8; 0; 0) 

 Appendix formulas [37] and [38] • The resulting lines have the same parameters 

 9> , t, K; nevertheless the resistance functions S(y) differ appreciably. Other- 

 wise expressed, in such cases it is not possible to fix the resistance proper- 

 ties of lines even by three parameters. 



The two families discussed characterized by K < are typical for 

 hulls run at F < 0.25- The absence of a parallel middle body is an important 

 feature. 



An inspection of the S(r) or S^(>') curves. Figure 24, page 45, ex- 

 plains formally why in the ascending branch of the first hump higher pris- 

 matics and t values are beneficial: Both tend to shift the steep rise of the 

 curves to the left towards higher Froude numbers. This property of shifting 

 is valid for smaller Froude numbers too, but here the effect mentioned is 

 canceled by others. 



