the suspension system (cable or pipe for 20- to 100-ton loads; pipe only for 

 400- to 600-ton loads) until contact is made with the sea floor. The initial 

 load will be equipped with an acoustic beacon or it will be designed to have 

 good sound-reflecting properties. For the former case, a sonar receiver 

 attached to the second load (or to the end of the suspension system) will 

 measure the relative displacement of the two loads and will instruct the 

 surface vessel's dynamic positioning system to make appropriate position 

 corrections. If the first modular load is not equipped with an acoustic 

 beacon, the vessel position correction will be controlled by an echo-ranging 

 sonar system similar to the one developed by the AC Electronics Corporation. 



Both of these systems have merit for affecting "coarse" load position- 

 ing, i.e., alignment of loads to within several feet of each other. Final 

 alignment will be monitored by a manned or unmanned submersible. The 

 submersible will observe only and will make no attempt to translate or rotate 

 suspended loads. The loads will have keyways, female/male connectors, or 

 studs which will align and guide sections to form interlocking units. 



The foregoing load positioning, guidance, and integrating system is 

 within the current state-of-the-art. Further operational details are not 

 warranted at this time due to the existing uncertainty regarding future 

 undersea construction missions and load configurations. None of the other 

 heavy-load positioning systems (high-thrust submersible, bottom crawler, 

 guidelines, and bottom supported winches) are considered to have the 

 potential for success exhibited by the chosen systems. 



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