the beach, reference 12. Therefore, the small, the medium, and the large 

 anchors may be expected to hold only about 1,740 lb, 4,600 lb, and 6,600 

 lb in the harbor, respectively. 



Holding Capacity of the Mooring Systems 



The holding capacity of an entire mooring system depends upon 

 the holding capacity of the anchor, the ratio of the length of the 

 mooring line to the depth of water, the type of soil in the harbor, and 

 the weight of the link chain at the anchor. The effect of these factors 

 upon the overall effectiveness of these mooring systems was estimated 

 as follows : 



First, for the purpose of these tests, the harbor was assumed to 

 have a sandy soil, as noted earlier. The effect of other types of soil 

 will be estimated later. Second, the length of the chain in each of the 

 three mooring systems. Figures 24, 25, and 26, was too small to make 

 a meaningful contribution in reducing the angle between the mooring 

 line and the bottom terrain. Their effect was, therefore, neglected. 

 Third, although Figures 24-26 show these mooring systems to be suitable 

 in up to 100- ft depths, most harbors have water depths less than 50 ft. 

 Therefore, a maximum water depth of 50 ft was assumed in these 

 calculations . 



The 315-ft nylon line of the small mooring system and the 420-ft 

 nylon lines of the medium and the large mooring systems yield angles of 

 approximately 9.1 and 6.8 degrees with the horizontal, respectively. 

 For a 6-degree angle, the holding power of the anchor is reduced by 

 about 15 percent whereas for a 12-degree angle, the holding power of the 

 anchor is reduced by about 38 percent, references 10-12. Therefore, 

 for the small, medium, and large mooring systems, the holding powers of 

 the anchors was assumed to be further reduced by approximately 27 

 percent, 15 percent, and 16 percent, respectively. Therefore, the 

 holding powers of the small, medium, and large mooring systems shown 

 in Figures 24, 25, and 26, in a sandy seafloor, with a water depth of 

 50 ft , may be assumed to be only approximately 1,300 lb, 3,900 lb , 

 and 5,500 lb , respectively. 



In a water depth of 100 ft, the angle formed by the mooring line, 

 with the horizontal, of the small, medium, and large mooring systems 

 will be 18.5 degrees, 13.8 degrees, and 13.8 degrees, respectively. 

 At these angles, it is quite likely that the anchors may not bury in 

 the sand at all. 



The holding capacities of the anchors in clay or a silty 

 seafloor may be lower by a factor of 3 to 7 than those estimated in 

 sand as a result of the beach test, references 12-13. If a factor of 

 7 were used to determine the holding capacities of anchors in mud, 

 then the small, medium, and large mooring systems could only be able 

 to hold less than 190 lb , 560 lb , and 790 lb , respectively. Most 

 harbors, of course, do not have a pure clay or a pure sand seafloor. 



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