Newman 



-• NORRBIN (L/T = 17.5) 

 — THEORY (HU) L/T = 20 

 -« MOTORA AND FUJINO u)' ~ 15 (L/T 



-4 (J= 

 -A ai'= 0,10 

 -■ ai'= lO" 

 L_ 



18 7) 

 V LEEUWEN (L T = 17 5) 



0.2 3 

 FROUDE NUMBER ^ / \^ 



4 



Fig. 7 - Comparison of theoretical side 

 force with various experiments (an as- 

 terisk denotes experinaents with bare 

 hull; in all other cases the data is for 

 base hull with rudder) 



Figures 7 and 8 show a comparison of Hu's results with experiments. The 

 theoretical curves in these figures are as computed by Hu for a rectangular flat 

 plate of length-draft ratio L/T = 20. The experimental results are for some- 

 what different values of the length-draft ratio, and to account for this discrep- 

 ancy the force and moment have been non-dimensionalized in terms of the square 

 of the draft, so that according to the classical low aspect-ratio theory the re- 

 sults should then be independent of the length-draft ratio at zero Froude num- 

 ber. The side force is shown in Fig. 7, and it is seen that there is relatively 

 poor agreement between the various results, both with respect to a comparison 

 of the theory and experiments and with respect to a comparison of the experi- 

 ments themselves. The corresponding situation for the moment, as shown in 

 Fig. 8, is much better and here the agreement not only between the various ex- 

 periments but also between the experiments and the theory is quite striking. It 

 is remarkable that the moment, rather than the force, should be in a satisfactory 

 state unless there is a substantial amount of separation confined to the midship 

 area of the hull which influences the force but not the moment. With regard to 

 the experimental results, both van Leeuwen and Motora and Fujino used a Series 



218 



