51 



Figure 29 - Changes in Bow Sections Above the D.W.L. 



Within the range of normal midship section forms, similar to parab- 

 olas of higher degree, Z(f) = 1 - f", it is found that the wave resistance is 

 not sensitive to changes of pure shape of section when the area is kept con- 

 stant. Thus, contrary to the conditions valid for water lines, the resistance 

 qualities of the midship section can be determined in normal cases by the 

 single area coefficient p. Under more general assumptions, the following 

 asymptotic laws are valid: 



a. When F becomes infinite; 



R ~y3' 



[25: 



b. When F tends towards zero. 



R is independent of fi 



H T_ 



[26] 



For finite F, R depends upon P, on the ratio -f- "^ and on the function X(^). 

 Thus no simple rule for calculating R as function of yS can be given. Neglect- 

 ing, however, the dependence upon X(f), as in the case of draft, interpolation 

 formulas of the type 



R~/SP^^^ [27] 



