How the mooring-system elasticity affects the peak mooring force is shown 

 in Figures 46, 47, and 48. In each case the water level is fixed and only the 

 mooring-line flexibility is changed. A substantial increase in F is noted 

 when the six-tire mooring-force damper is removed and replaced with a rela- 

 tively inflexible section of conveyor belt (i.e., switching from the MS-1 to 

 the MS-2 system) . This is apparent in Figure 47 where the MS-2 data are shown 

 with relation to the MS-1 curve from Figure 46; all the data are above the 

 MS-1 curve with much of the data far above it. The MS-3 data and curve- 

 through data are shown in Figure 48. This system results in forces that are 

 somewhat higher than those for the MS-1 system but lower than those for the 

 MS-2 system. The corresponding values of K are provided in Table 4. 



b. PT-2 Breakwater . The PT-2 module was tested only in the MS-3 mooring 

 configuration; test results are shown in Figures 49 and 50. Again as for PT- 



1, the force is proportional to H n , but for PT-2 the appropriate exponent is 



2, not 3/2 as it is for PT-1. The curves for n = 2, fitted by eye, are shown 

 in Figures 49 and 50; the corresponding values of K are listed in Table 4. 

 Although PT-2 was tested with the MS-3, and not the preferred MS-1 mooring 

 system, the effect of a change from MS-3 to MS-1 may be estimated by assuming 

 that the ratio of the respective forces is the same as for the PT-1 module 

 (for which such data exist and are conveniently summarized in Table 4). For 

 PT-1 it is noted 



K(MS-l) _ 280 _ 

 K(MS-3) 370 



Assuming that this ratio holds for the PT-2 module as well, the estimated MS-1 

 values, shown in Table 4, are obtained. Although the peak mooring forces for 

 the PT-1 module are higher than those for the PT-2 module for the same wave 

 height and water depth, it should be noted that the transmitted wave is also 

 smaller in the case of the PT-1 module. 







PT- 

 MS- 



1 

 2 



1 











0/d = 0.22 



450 













^ 



°° 



o 

 o o 



O A 



^k/ 



_ 375 









o 







a 





' 



£ 















o a 



i / 





i 300 









a ° 



° 



& 



- 





- with damper (MS- 1 ) 



■o 

 a 

 o 

 ^ 225 



a 



a. 









a o 







& 



o 



O 3 



° 6. 



a 



o 



i. / 





LEGEND 



150 



L/B 











° / 











o 2.5 1o 4.2 



75 



















A I . 7 to 2.4 

 • I. 3 to I .6 

 + I.O to 1. 2 



.25 .50 .75 IJ0O I25 :50 I.75 200 



Incident Wave Height H (m) 



Figure 47. Effect of mooring-system compliance on F 

 (MS-1 and MS-2, d = 4.7 m) . 



47 



