Conversely, piles would serve well as OTEC anchors if high mooring 

 line angles were adopted for the OTEC system. There are several reasons 

 why high mooring line angles should be avoided. First, high mooring line 

 angles mean increased mooring line forces: for a mooring line angle of 

 0.79 rad (45 deg) the line tension would be 1.4 times the tension for a 

 line angle of 0.0 rad; for 1.0 rad (60 deg) the line tension would be 

 twice as large. Note that there is not a mooring line available to hold 

 OTEC even at a zero line angle. Raising the line angle increases line 

 tension and compounds the mooring line problem. High line angles also 

 stiffen the mooring which increases dynamic loading at the anchor. In 

 moorings with low line angles, most of the dynamic loading is damped out 

 before reaching the anchor by line motion in the water. Preliminary tests 

 at University of California, Berkeley, suggest that dynamic loadings could 

 result in significant strength reductions in the calcareous ooze sediments 

 that predominate in proposed OTEC siting areas. Thus, dynamic loadings on 

 anchors on calcareous ooze should be minimized to prevent soil strength 

 reductions and anchor pullout. High mooring line angles and resulting 

 high dynamic stresses at the anchor should be avoided. 



Pile anchors may serve well to moor OTEC to a rock surface such as 

 exists beneath some parts of the Gulf Stream. The pile sections designed 

 are really steel shear pins which are grouted into rock to provide addi- 

 tional resistance against uplift. 



Plate Anchors 



Plate anchors (direct embedment anchors, screw anchors, etc.) are not 

 suitable for providing the holding capacity required for OTEC in either 

 loading environment. For example, in the deep ocean environment, (assuming 

 a zero degree line angle at the seafloor) restraint of OTEC would require 

 a square plate 6.1 m (20 ft) on a side embedded to a soil depth of 30 m 

 (100 ft). To key a 6 m direct embedment fluke approximately 12 m of travel 

 would be necessary. Thus, the initial penetration required of the fluke 

 would be 30 m + 12 m = 42 m (140 ft). A propellant system for embedding 

 these flukes is considered not feasible. Other driving systems, while 

 feasible, would require a complex and very large driving guide on the sea- 

 floor and would require considerable equipment development to guarantee 

 the project. 



Please note that the above deep ocean loading assumes a horizontal 

 loading. Increasing the mooring line angle would increase the number of 

 6 m plates required, and would necessitate bridling to equalize the load- 

 ing. CEL has performed this task in shallow water where assembly could be 

 accomplished subaerially, but installing and bridling flukes remotely, in 

 deep water would be extremely complex and expensive. 



Standard Burial Anchors 



Drag embedment anchors could be fabricated to provide the required 

 holding capacity for OTEC in the benign, deep ocean environment. 



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