The chosen approach entails consideration of common relevant factors 

 and combinations of these factors. Inherent in this technique is the need for 

 bounding the problem, i.e., limiting the number of alternatives. After 

 gathering and weighing evidence during the initial stages of the project, it 

 was found that familiarity with the following four subject areas would 

 permit meaningful evaluations of virtually all the candidate systems; 



1. Surface vessels 



2. The use of pipe to suspend the load 



3. The use of cable to suspend the load 



4. Methods of supplying buoyancy to the load 



The task team was organized to locate relevant technical and environmental 

 data needed to carefully analyze these four subjects. When necessary, 

 calculations were made in enough detail to answer specific questions on the 

 effects of environment and similar factors on system performance. 



Surface Vessels 



All candidate heavy-lift systems require a surface vessel in some form. 

 For ease of distinction, two types of surface craft are considered: platform 

 and ship. Platforms are characterized by their very deep drafts when in the 

 operational mode, while for ships most of the hull is near the water surface. 



Five representative surface craft were investigated for their 

 suitability as a component in the heavy-lift system. The dimensions and 

 cost of these vessels are presented in Table 2; detailed descriptions are in 

 Appendix A. 



Three of the vessels were investigated in some detail: the FORDS 

 platform, T-2 tanker, and the C1-M-A VI ship. The characteristic responses 

 of these vessels in various seas, the effects of the vessel motions on the 

 system in question, and similar points were given attention. By way of 

 summary, the following important points can be made. 



SI 



Availability. There are many ships suitable and available for conver- 

 on to heavy-lift operation. In some cases, the conversions are relatively 

 minor. There are very few, if any, available and suitable platforms. A 

 platform fitting the needs of the project would definitely be a custom-built 

 item. 



Ease of Construction. There is much more experience in building 

 ships than platforms. The result is that it is easier to design and build an 

 acceptable ship. The limited experience in designing and constructing 

 platforms has made this type of vessel relatively expensive to build. 



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