4. The control subsystem, which includes the controls of all sub- 

 merged and surface equipment and any required instrumentation such as 

 attitude sensors, safety alarms, etc. 



5. The load handling and surface support subsystem, which includes 

 the cable, winch, surface vessel, crane, etc. 



The most influential requirement related to the physical configura- 

 tion of the pile emplacement system is that several piles be emplaced 

 in a given pattern. This necessitates the use of a template to properly 

 position the piles, because the cost and difficulty involved in remotely 

 positioning separate piles in a pattern in 6000 feet of water would be 

 unreasonably large. The template provides a temporary base for power 

 conversion and control equipment and acts as a guide to maintain verti- 

 cality of the piles. It also can be designed to remain in place as part 

 of the major structural support system. Thus, the seafloor installation 

 need not have as heavy a base structure, and the installed weight of the 

 installation can be reduced. 



The template will constitute a major portion of the weight of the 

 emplacement system. Since all of the conceptual designs were based 

 upon essentially the same installation plan dimensions, the weight of 

 the template can be taken as constant. Differences in total system 

 weight are thus due to differences in the weight of the emplacement 

 mechanisms, the piles, and possibly the instrumentation and control 

 systems required. The pile weights may vary because of different 

 cross-sections and lengths required to obtain the specified load 

 capacity. 



Because the piles are designed to be normal to the template the 

 requirement concerning pile verticality is essentially a requirement 

 for a maximum inclination of the template of + 2 degrees. It was 

 concluded that the installation system would hang from the cable in an 

 essentially vertical condition. Thus, if the piles are allowed to free- 

 fall the final 3 to 5 feet they will enter the soil approximately 

 vertically. This can be accomplished by providing a bottom-sensing 

 probe and trip mechanism to release the piles. Also, a supplementary 

 footing may be necessary to stabilize the template while one of the 

 piles is being driven. The bottom-sensing probe and supplementary 

 footing are shown in Figure 1. 



It was determined that hydraulic power is the optimum form for each 

 of the three emplacement mechanisms. The use of hydraulic power at the 

 planned water depth is not common, but the state-of-the-art was advanced 

 considerably by the design for the NCEL seafloor deep corer-^. It was 

 determined that the best method of supplying power was by electrical 

 transmission from the surface to a submerged electric motor driving a 

 hydraulic pump^. This eliminates the difficulties involved with 



