Mori s Inui and Kajitani 



wave profiles of the two tested models M 20 and M 21 for the twelve 

 speeds K Q L = 7 through K Q L = 20. 



In this procedure, the measured wave profiles at twenty po- 

 sitions x = - 0. 95, - 0. 85, ... , 0. 95 are adopted as the principal 

 input data. 



In addition, some selected readings of the wave recorder 

 on the longitudinal cut line y = 0. 25 (x = 1. ~2. 0) are adopted as 

 the supplemental input data, which are useful for the definite deter- 

 mination of the source around the stern. 



Figures 10 ~12 show the wave-analyzed sources m( £ ) of 

 M 20 and M 21 for the three selected speeds K Q L =8, 12 and 16, 

 where the hull generating source m( £ ) is also given for comparison. 



Because of a very low level of wave elevation, the accuracy 

 of wave analysis is rather poor with the thin model M 20, particular- 

 ly at the lower Froude number Fn < 0. 2887 (K Q L > 12). 



In Figures 13 and 14, the similar results at K L =10, 

 11 and 12 are summarized with M 20 and M 21, respectively. 



From Figures 10 through 14, a clear discrepancy, which 

 is roughly proportional to the beam-length ratio of the models, is ob- 

 served between the wave -analyzed source m( £ ) and the hull-gene- 

 rating source m( £ ). 



For the convenience of further studies including the effect 

 of Froude number, the ratio of the two kinds of sources, or the cor- 

 rection function a ( £ ) = m( £ )/rn( £ ) is calculated with the wide 

 model M 21. 



The results are reproduced in Figures 15 ~ 17. 



Here it must be remembered that the relative accuracy of 

 a ( £ ) is poor around midship, because of m( £ ) being null for 

 £ = 0. 



With respect to the sheltering effect, the present authors 

 E*] • [^] - [3j suggested a simple, empirical correction, like 



*($) = 1 - M ( 1— U I ) (14) 



692 



