There are, basically, no differences in the equipment or operational 

 procedures among the systems using cable nor among the systems using pipe. 

 It was assumed that the pipe handling equipment on the ship with pipe string, 

 for instance, is exactly the same as that on the platform with pipe string. 

 Thus, the differences between systems employing the same suspending 

 medium are confined to the differences between surface vessel characteristics 

 and the effects of these characteristics on system performance. 



Operational procedures for these systems follow the tried and proven 

 methods for lifting and lowering heavy loads. For the systems using cable, 

 the load is suspended on one or more cables and lowered to the desired 

 depth. In both the platform and ship it is assumed that a centerwell, 

 amidships and open to the sea, is provided. No crane-type operations 

 employing cable are investigated since the use of a boom was determined 

 to be highly undesirable. In addition to the cable, all aspects of the winches, 

 sheaves, and associated operations during usage are given careful scrutiny to 

 determine the feasibility and desirability of utilizing cable on a ship or 

 platform to satisfy the needs of the proposed heavy-lift system. 



The operation of a system using pipe to support the load is very 

 much the same as for cable. The same basic surface vessel is stipulated, i.e., 

 one with a centerwell, but a single pipe is used to support the load. More- 

 over, there are the obvious additions of a derrick and the accompanying pipe 

 handling equipment. The basic configuration is identical to that of the 

 current fleet of mobile offshore drilling rigs. Cuss I is an example of this 

 type of pipe system installed on a ship-like vessel, and the ill-fated MOHOLE 

 platform exemplifies what is meant by "platform with pipe string" in this 

 study. All facets of constructing and operating a system using pipe as the 

 supporting medium are given consideration in the sections to follow. 



Buoyant Assist. During the course of the study it was found highly 

 desirable, if not necessary, to decrease the total load in the cable systems. 

 Therefore, an external means of increasing the buoyancy of the load, thereby 

 decreasing the total tensile force in the cable(s), is considered an important 

 subsystem in the ship/cable and platform/cable systems. Various methods 

 of providing this buoyancy are investigated. Cable systems employing these 

 methods are said to have "buoyant assist." 



Unconventional Surface Craft 



Of the unconventional surface-supported systems, the hydrodynamic 

 winch is given the most attention in this report. ^-^ The hydrodynamic winch 

 consists of a very large cylinder the interior of which is divided into 



