DESCRIPTION OF MODELS 



To match the assumptions used in the mathematical representations 

 for predicting the dynamic loads and motions in mooring lines, an ideal 

 material for model experiments would be completely flexible in bending 

 and would have a smooth, cylindrical surface. 2 To provide measurable 

 tensions, the line also would have to be heavy. No material was readily 

 available which would meet all of these requirements. As a result, the 

 five sample materials illustrated in Figure 3 were chosen arbitrarily. 

 The physical characteristics of the samples are listed in Table 1. The 

 r lative acceptability of the samples in terms of three physical charac- 

 teristics are listed in Table 2 to permit comparison. The open link 

 chain is flexible in bending and heavy; but does not have a smooth 

 cylindrical surface. The mercury filled tube has a smooth cylindrical 

 surface and medium weight, but is stiff in bending and tends to kink. 

 The bead chain is flexible, but is light weight and does not have a 

 smooth cylindrical surface. The wire rope is nearly smooth and 

 cylindrical, but is light weight, stiff, and tends to kink. On the 

 other hand, the weighted nylon cord is flexible, smooth and cylin- 

 drical, and heavy. In addition, the nylon cord has extensibility 

 similar to that of the prototype synthetic mooring lines. The weighted 

 nylon cord is most like the synthetic lines used in the full-scale 

 moorings, -q- 



EXPERIMENTAL ARRANGEMENT 



MODEL CONFIGURATIONS 



The model experiments were conducted in the Circulating Water Channel 

 which has a working depth of 9 feet. The general mooring arrangement is 

 shown in Figure 4. The lower end of the mooring line was secured to a 

 tie-down block on the bottom, with the upper end secured to a two- 

 dimensional force dynamometer mounted on a slider arm. The slider arm 

 is driven vertically in a sinusoidal motion with a fixed amplitude of 



