l^ave Induced Faroes and Motions of Tubular Structures 



The model response Is shown in Figs. 8-10 for waves mov- 

 ing parallel to the X-axis. The first two of these figures show the 

 mooring tension variations , and the last shows the surge motion 

 versus wave period. In each case the ordinate is the double ampli- 

 tude of the force or motion in question divided by wave double ampli- 

 tude, thus the amplitude of the transfer function obtained from a time 

 series analysis of the random wave tests. Points on the figures dis- 

 play these random wave results for three significant wave heights 

 within the applicable range of periods for the "A" and "B" spectra. 

 Also shown on these figures are results from experiments in regular 

 waves , and theoretical predictions. 



It is interesting to note that the random sea tension variation 

 results display an apparent amplitude dependence in the range of 

 longer periods. This is the range in which drag forces would be 

 most strongly felt and no doubt points to a possible deficiency in 

 the process of linearizing the drag force. 



As before, the surge motion shows very good agreement 

 between experiment and theory. 



0.2 0.6 1.0 1.4 1.8 2.; 



WAVE PERIOD IN SECONDS 



2.6 



Fig. 8. Tension variations in anchor leg 2 



1107 



