Stability. The stability of the surface craft is very important. 

 Platforms are inherently more stable than ships in every response mode; 

 this is the main reason they are used. Large ships are fairly stable under 

 most sea states and would be acceptable if a restricted range of operating 

 environments is acceptable. 



Accommodations. The amount of space available for equipment and 

 personnel is an extremely important factor. Small ships are out of the 

 question for this project simply because they do not have enough room for 

 all of the equipment needed for a cable system or pipe string and derrick 

 system. Larger ships may be large enough to accommodate the derrick and 

 pipe string or cable equipment, but there are some limitations on the size 

 of the load. 



Platforms are considerably larger than ships. They are clearly 

 superior to ships in that they are not restricted by beam width and deck 

 space. Moreover, it is much easier to build a platform with a large centerwell; 

 for a ship there is obviously a restriction on how large the well can be. For 

 example, the Glomar Challenger has a beam of 65 feet, yet the well is only 

 20 by 22 feet. 



It is apparent that as the load increases in size, the feasibility of using 

 a ship to transport and lower it decreases accordingly. Much larger loads can 

 be transported on and lowered from a platform. However, this is important 

 only if it is necessary for the lift system to be self-contained. It is planned, 

 for instance, to use the Glomar Challenger to lift loads larger than the 

 20 by 22 foot well by transporting the load in a separate barge, which will 

 lower it under the Challenger where the pipe string can be attached. While it 

 is desirable to keep the operation down to one self-sufficient ship, the size 

 limitations of a ship's centerwell can be overcome, if necessary, by transporting 

 the load in a suitable barge. 



Type of Operation. There appear to be two general types of 

 operations which could be encountered in heavy-lift operations: (1 ) fast 

 placement or recovery of objects on the ocean floor or (2) a test operation 

 where a subsea system or component is held at depth for testing (similar to 

 the FORDS platform). As far as the surface vessel is concerned, these 

 distinctly different operations are not compatible. For the first type of 

 operation, i.e., lowering or recovery, a ship would be satisfactory — assuming 

 the crew were given some leeway in the timing of the operation. For the 

 second type of operation, simply holding a test specimen, there is probably 



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