(2) For the stiff models, load ratios decreased 

 with increased preload. 



c. Load ratios increased with current, and 



d. Load ratios decreased with increasing cable scope. 



4. The motional responses of the model moorings were 

 influenced by bending stiffness in that: 



a. The flexible models exhibited mostly traveling 

 waves in the plane of the cable catenaries which 

 were continuously reflected up and down the cable. 



b. The stiff models exhibited strong nodal motions 

 with standing waves both in and out of the plane 

 of the cable catenaries. 



5. The stiff models also exhibited more tendencies toward 

 distorted and highly peaked load responses than did 

 the flexible models. 



6. For deep sea moorings where the watch circle is to be 

 minimized the above conclusions indicate that the best 

 mooring line material is flexible in bending. The pro- 

 totype lines shown in Figure 1 and 2 are flexible, with 

 the added advantage that they also are extensible. 

 Extensibility provides cushioning of otherwise large 

 transient loads during deployment. Anchor chain is 

 added to the bottoms of these systems to prevent 

 chafing of the synthetic lines. Additionally, the 

 experimental results indicate significantly reduced 

 dynamic loads with the chain on the bottom. 



Although some of the experimental results have been used to validate 

 the prediction technique for dynamic responses presented in References 

 2 and 4, the weighted nylon cord results were not used, but the flex- 

 ibility and extensibility of the weighted cord match the characteristics 

 of the prototype mooring lines better than do the other models. Therefore, 

 1t is recommended that the weighted cord results be used to validate the 

 dynamic prediction techniques. 



48 



