Pi en and Lee 



the same as built. With this in mind, struts were modified to remo- 

 ve the cause of flow separation. This was done simply by cutting off 

 the blunt endings in order to save time and effort in the shop. The 

 corresponding source distribution was as follows : 



m(x) = 3.4533x 2 - 54. 2007x 3 + 287. 262x 4 - 702. 9402x 5 



L n Q Q 



+1106. 1540x +I642.7120x -1586.4090x + 477. 3101x 



for forebody. 



The afterbody singularity distribution was such that a sym- 

 metrical strut was obtained. Figure 17 gives the waterplane of the 

 modified strut. The modified demihull was tested alone in the capti- 

 ve condition, i.e., restricted from heaving and pitching. Figure 18 

 shows the comparison between C w and C r curves and, again, 



the agreement is quite good. 



The strut was further modified to regain the waterplane 

 area lost in the first modification. Figure 19 shows the strut water- 

 plane after the second modification. The corresponding source dis- 

 tribution is given as follows : 



m(x) = 22. 8204x 3 - 447. 7026x 4 + 3276. 9175x 5 - 11883. 5996x 



+ 23318. 8100x ? - 23199. 7132x 8 + 5282. 0771x 9 



+ 11396. 83 66x - 10699. 508 lx l + 2933.42 72x 



for forebody. 



The strut was again kept symmetrical with respect to the 

 middle length. Figure 20 shows the comparison between C w and 

 C r . The agreement is also good. 



At the present time, a SWATHS with proper camber is under 

 construction. The strut with the second modification, Model 527 6-E, 

 is used for the catamaran configuration. At a later date, another 

 demihull without camber will be built and tested in a catamaran con- 

 figuration in combination with Model 527 6-E. After these additional 

 experimental results are obtained, the influence of camber on resis- 

 tance can be assessed. 



Figure 21 gives the resistance comparison between two 

 single hulls, Model 5276-C and Model 5276-E, at a 32-ft draft. To 



504 



