4. Retrieve the unit at a later date. 



5. Return the unit to port. 



These goals establish the major functions of the system and serve as a useful 

 frame of reference for system conceptualization. 



In an effort to provide an objective assessment of future underwater 

 technology, the scenario discussed above, i.e., that of transporting, placing, 

 and later retrieving one self-contained load, is based on projections of near- 

 term installations. It is felt that as experience increases in placing this type 

 of load, the task of assembling multipart, module-type loads will be closer to 

 the realm of possibility; and the operational techniques and procedures for 

 fulfilling the more complex task of assembly will be designed on a more 

 knowledgeable and experienced basis than is presently possible. 



Since it is highly probable that there will be a transition from 

 single-unit loads to modular construction, an investigation of the latter is 

 necessary for accurate definition of future problem areas. It is, therefore, 

 considered essential to discuss the problems of transporting, guiding, and 

 positioning loads once they are on the sea floor. Systems performing these 

 tasks will follow a more advanced scenario than the single lift-or-lower 

 operation: 



1 . Transport or receive from auxiliary vessels the components 

 (modules) of an underwater structure. 



2. Place and assemble the modular units on the ocean floor. 



3. If necessary, enable the completed structure to be monitored, 

 controlled, and serviced. 



4. Disassemble and retrieve the units at a later date. 



5. Transport (or transfer) the units to a port (or auxiliary vessels). 



The primary differences between this and the first scenario are: 



1 . The more advanced system should be capable of receiving and 

 transporting loads from auxiliary vessels at sea. 



