Relative Merits of Pile and Deadweight Anchors. By process of 

 eliminalioD, then, pile and deadweight type anchors remain as more 

 suitable for use for OTEC. The relative merits of pile versus dead- 

 weight anchors, as applied to mooring OTEC, have been presented thoroughly 

 elsewhere (2,3,6]. What follows are brief summaries of the relative 

 merits of these anchors in each ocean environment being studied. 



In the typical deep ocean soil profile, piles offer a low lateral 

 load versus material weight efficiency, the efficiency being only slightly 

 better than that of deadweight anchors. The installed cost of the pile 

 system would be higher than that of the deadweight. Further, installation 

 of the pile group anchor is more complicated and requires a longer 

 weather window. For these reasons, the deadweight anchor was selected 

 as the better anchor type for use in the deep ocean. 



When the pile and deadweight anchor types are sized to resist the 

 loadings of the Gulf Stream environment, the efficiency balance is noted 

 to shift quite markedly toward pile-type anchors when on rock seafloors. 

 The seafloors beneath the Gulf Stream, where the Stream is close to 

 land, frequently are rock. These high-strength, near-surface materials 

 can be utilized to resist the high horizontal load component. Thus, the 

 pile section design can be changed considerably, thereby significantly 

 increasing the efficiency of the pil-e-type- anchor— over -that of the 

 deadweight. A modified pile anchor design for use in hard seafloors 

 will be presented latei in this report. 



Anchor Lowering 



The above discussion considers only in-place, service performance 

 of the pile and deadweight anchor types. These anchors, or components 

 of them, must be transported to an OTEC anchor site and then lowered 

 through the water column and safely emplaced on/in the seafloor. 

 Assuming a mooring line angle of 0.8 rad (45 deg) at the anchor, the 

 deadweight anchor for the deep ocean environment will weigh about 31 MN 



