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on an anchoring technique which is not particularly efficient for very 

 large sized plates; e.g., 3 m on a side, because of the embedment dis- 

 tance given up during keying of the fluke [2,3]. 



(2) Drag embedment anchors . Drag embedment anchors were eliminated 

 as a contender because these anchors require a near horizontal mooring 

 line at the seafloor during embedment or "setting". This near-horizontal 

 mooring line can be achieved only by supplying sufficient deadweight 

 ahead of the anchor, in the form of heavy chain or sinkers, to balance 

 the vertical load component in the mooring line to the platform. It is 

 this configuration that is most commonly used to moor drilling platforms 

 (ship, semisubmersible) , but drilling platforms are operating in much I 

 shallower water depths than those of the proposed OTEC plants. As will 

 be shown in the "Anchor Lowering" section, lowering of the required 

 deadweight (chain, sinkers, etc.), weighing perhaps 9 to 18 UN (2 x 10 

 to 4 X 10 lb) is a difficult task, requiring special heavy lift equip- 

 ment . - - — 



There are additional reasons for eliminating the drag embedment 

 anchor from further consideration. First, the drag embedment anchor 

 would be a poor performer in tbe case of a single-point moor because it 

 is not omnidirectional: The drag embedment anchor will pull out if the 

 direction of load is changed markedly as will typically occur in the 

 deep ocean environment. Second, industry is not capable presently of 

 manufacturing single anchors large enough to develop the required hold- 

 ing capacity for a mooring leg (assuming 1 to 12 legs). Thus, a group 

 of anchors, in tandem or in series, would have to be used at each anchor- 

 ing point with all the attendant problems of load handling and position- 

 ing in deep water. It is the first reason given, however, (i.e., the 

 large deadweight needed to balance the vertical component of load) that 

 is most significant in removing the drag embedment anchor from further 

 consideration for OTEC use. 



One anchor type - the Bruce - is advertised as maintaining 

 its embedment with load direction change, but this claim 

 remains to be verified for full-scale anchors. 



