2. Deadweight may be added to the mooring line near the anchor to 

 "absorb" the vertical component of mooring line load. The deadweight may 

 be mass blocks attached to the mooring line or may be a length of heavy 

 chain incorporated into the lower end of the mooring line. 



3. The drag embedment anchor could be fully embedded during installa- 

 tion using a long scope of line and zero mooring line angle, and then the 

 scope shortened considerably raising the line angle to 0.1 rad (6 deg). 

 Once embedded, the drag anchor will hold near capacity at this 0.1 rad line 

 angle. This approach presumes that it is possible to preset an anchor to 



a few million pounds. Developing the necessary lateral force may be poss- 

 ible by pulling one anchor against another, but it will be difficult and 

 time consuming. Further, if the preset load was exceeded, the anchor could 

 pull out. 



Given that one of the above options for achieving a near zero line 

 angle during embedment is invoked, an appropriate drag embedment anchor 

 could be built. An anchor such as the Bruce would be desirable because 

 it would reorient itself and embed regardless of initial attitude. 

 Maximum lateral capacity would then be limited to 9-16 MN (2-3.5x10^ lbs) 

 without resorting to multiple anchor hookups. 



Conclusions 



Of the two anchor types considered potentially applicable to OTEC, 

 the fluke and pick types, the least complicated installation would be 

 achieved with the pick type because of its ability to embed irrespective 

 of landing attitude. The maximum capacity of this anchor would be 9 to 

 16 MN (2 to 3.5 million pounds). If the more complicated installation 

 procedures associated with the fluke type are acceptable, then 13 to 22 MN 

 (3 to 5 million pounds) capacity is possible. For these anchors to be 

 useful, they would have to be used in multi-point moorings possibly with 

 several anchors in tandem or parallel in each leg. 



Until fabrication technology improves to a point where 114 Mg to 182 

 Mg (250,000 to 400,000 lbs) anchors are feasible, the use of conventional 

 anchors of the pick and fluke types would seem to be less attractive than 

 other types of anchors for the OTEC installation. 



PLATE ANCHORS 



Introduction 



Several plate anchors were designed and analyzed for holding capacity. 

 Calculations were made for seafloor soil categories A, C, and D. Possible 

 OTEC plate anchor designs were also compared to existing plate anchor tech- 

 nology. Rough cost estimates were made on the basis of present material 

 and fabrication costs. 



22 



