H I ,miu-nJuuLw. i im j i L ir m i , .n-iLU — ^ 



(7 X iO lb) in air and about 18 MN (4 x 10 lb) in water. Two basic 

 inS'ttallation techniques were considered: (1) controlled lowering in one 

 pi«ce or in five elements or (2) free-fall emplacement. 



Figure 4 graphically presents the state of the art in the handling 

 of heavy loads in the deep ocean. Two cases were considered for control- 

 led lowering. First, the deep ocean deadweight anchor was assumed to be 

 broken into five components, each weighing 3.6 MN (0.8 x 10 lb) sub- 

 merged. Second, the deadweight was assumed lowered as one unit weighing 

 18 MN (4 X 10^ lb) submerged. 



The drillship falls far short of the required lift capability. Even 

 'if the drillship were equipped with 100%-ef fective motion compensation, 

 it would be able to lower the desired anchor components only to maximum 

 depths of 2,000 m (6,000 ft). Of course such a motion compecsation 

 system is far from reality. 



The derrick barge, when coupled with a "pipe link" line, such as 

 that proposed for mooring the Lockheed OTEC platform (4], at first 

 glance appears to have significantly greater load-handling capacity than 

 the drillship. However, the crane barge load capacity plotted ia Figure 

 4 also assumes 100%-ef fective motion compensation, as with the drillship 

 load capacities. Further, the effect of sea and swell on the crane 

 barge capacities are much more pronounced than that on the drillship 

 capacities. In addition to its load capacity limitations, the cr.:;ie 

 barge technique for lowering the anchor is very limited in the lowering 

 rate that can be achieved. The time required to make and break the 

 joints of the pipe link chain is considerablv longer than that required 

 to make and break drill pipe joints: using the pipe link chain, lowering 

 a five element anchor to 6,000 m (20,000 fi:} will take in excess of 6 

 days. To make economical use 'f the derrick barge with its pipe link 

 chain, the anchor would probably have to be lowered as a unit, limiting 

 the maximum handling depth to about 2,000 m (6,000 ft). 



The comparison of state-of-the-art heavy-load handling systems 

 sho^ws that the Glomar Explorer is the only vessel capable of lowering 

 the Li MN OTEC anchor to water depths of 2,000 to 6,000 m (6,000 to 



