12 014 0.16 0.18 020 022 024 026 028 030 032 054 0.36 038 0.40 0.42 044 046 0.48 0.50 Q52 054 0.56 Q58 060 



Figure 2. (From Havelock [11], by permission of the Society of Naval Architects and Marine Engineers.) 



Comparisons of measured and calculated wave resistance for hull forms resem- 

 bling conventional ships have been carried out by Wigley, Weinblum, Lunde, Shearer 

 and others. For convenience in calculation most comparisons are made for "elementary" 

 ship forms with lines which can be expressed by simple polynomials. Figure 2 is from 

 a paper by Wigley and Lunde [2] and is also reproduced in papers by Havelock [11] 

 and by Birkhoff, Korvin-Kroukovsky and Kotik [1] (note that the resistance coefficient 

 is again defined differently). Figure 3 from a paper by Shearer [1] shows a com- 

 parison between computed and observed wave profiles for a given model at several 

 Froude numbers. In each case the qualitative behavior of the measured and calculated 

 curves is similar, and even the quantitative agreement is fairly good. Inspection of 

 comparisons of measured and calculated wave resistance indicates that in the neighbor- 

 hood of the first (counting from the right) hump the calculated curve generally lies 

 below the measured curve if the model is free to trim but above it if it is fixed in 

 position (the Stoker-Peters result mentioned earlier indicates that the linearized theory 

 is the same in either case). To the left of this hump calculated values generally seem 



118 



