Observations of motions in the mooring lines indicated differences 

 in behavior between the different model moorings. All models exhibited 

 motions in the plane of the steady-state catenary similar to those 

 illustrated in Figure 22. In all cases the most severe changes in cable 

 angle appeared at the fixed pivot, which was a reflection point for 

 waves traveling up and down the mooring line. The wire rope and the 

 mercury filled polyethylene tube, which were both stiff in bending, 

 exhibited well defined nodal patterns with standing waves similar to 

 the sketch shown in Figure 22. In traveling waves, the nodes move along 

 the line; whereas, in standing waves, the nodes remain in fixed positions 

 along the line. These patterns did not apDear to change witn frequency 

 and, hence, the patterns probably were related to kinks in these lines 

 rather than being results of resonance phenomena. The more flexible open- 

 link chain, bead chain, and weighted cord models exhibited mostly travel- 

 ing waves which began at the top, reflected from the fixed pivot, and 

 returned to the top. The stiff models exhibited significant motion normal 

 to the plane o^ the catenary, especially near the fixed pivot. The flex- 

 ible models exhibited none of this out-of-plane motion, except for the 

 weighted cord which exhibited a higher frequency small amplitude wiggle 

 out-of-plane. This may have resulted because the cord was weighted with 

 discrete masses in the form of lead shot. As a result, the out-of-plane 

 wiggle could have been pendulus motion of these weights. 



As to cases where mooring line was allowed to lie on the bottom, 

 the motions were diminished by the removal of the fixed pivot which had 

 acted as a wave reflector. 



CONCLUSIONS AND RECOMMENDATIONS 



In terms of the objectives of the above experimental program, the 

 following conclusion is drawn: 



?f i. The variety of conditions listed in Table 4 and Appendix A 



|H , indicate that sufficient data were taken to validate the 



analytical methods for predicting the dynamic loads in 

 mooring lir.es with forced vertical motions at the tops 



