CONCLUSIONS 

 Lifting and Lowering 



1 . The use of pipe to suspend, lift, and lower loads is the most feasible 

 method of those considered for satisfying the goals of the heavy-lift project. 

 An acceptable system would most likely resemble the mobile offshore drilling 

 vessels presently operating in many parts of the world. 



2. The surface vessel required for support of a heavy-lift system can be either 

 a ship or platform. The characteristics of these vessels generally have little 

 influence on the performance of the lift systems considered in this study. 



3. The feasibility of using cable to suspend, lift, and lower loads weighing 

 greater than 1 00 tons to depths greater than 1 ,000 feet is judged to be 

 significantly less than for pipe. 



4. An effective and efficient method of supplying buoyancy to very large 

 loads poses unsolved problems. 



5. Lowering and raising 200 tons to 6,000 feet will be a near-term capability. 

 At least one commercial vessel will have the capacity to perform this task in 

 the very near future; drill pipe will be used as the suspending medium. 



Positioning and Guidance 



6. Positioning suspended loads by displacement of the surface support 

 vessel is the most feasible means for coarse alignment at depths to 

 6,000 feet. 



7. An echo-ranging sonar system or a system comprised of an array of sea 

 floor acoustic beacons with a load-mounted receiver, are considered the most 

 promising approaches for guiding the surface support vessel during emplace- 

 ment, and are commercially available. 



8. Fine alignment and integration of modular loads can best be achieved 

 through the use of keyways, studs, or other load guide appurtenances. 



9. A manned, deep diving submersible could serve as a positioning and 

 guidance backup system supplementing, if need be, alignment corrections 

 provided by the prime acoustic guidance system. 



