150 



It is recommended that a program be initiated which seeks to: 1) tabulate the 

 variety of tasks which divers now perform and will perform in support of 

 development and production of deep (greater than 400m) offshore oil and gas; 

 2) identify which of these tasks can be performed only by human intervention; 

 and 3) commence design of a manipulative system which will possess the dexterity 

 and force-feed back information required to substitute for the diver. 



6.3.3 Navigation 



Current acoustic navigation/positioning systems provide adequate information 

 external to a structure. However, inside a steel- jacketed structure rever- 

 beration caused by the structure members limits use of acoustic techniques to 

 the external members. A navigation system is required which will permit vehicle 

 positioning within the interior of a structure. Several alternatives to long 

 and short acoustic baseline techniques are available which may provide the 

 positional data required. Inertial guidance has already been mentioned, it 

 should be investigated for application to structure navigation, if it is 

 unacceptable, the reasons should be identified and made available to the ROV 

 community. Another technique could involve imparting memory to the ROV in which the 

 coordinates of nodal points are imparted into a computer which directs the 

 vehicle to various points inside the structure. High accuracy doppler sonar - 

 where the acoustic pulses are reflected off a specific member - may also offer 

 an alternative technique. These and other techniques, should be investigated 

 and evaluated with the ultimate goal of providing in-structure navigational 

 data for inspection and maintenance tasks. 



6.3.4 Free- swimming/Towed Vehicle 



Towed vehicles are constrained from performing a great number of additional 

 tasks by virtue of their inability to stop, maneuver independently of the surface, 

 and collect samples or perform manipulative functions. In several applications, 

 such as geological/biological surveying, and waste site disposal investigations, 

 selective sampling and detailed site investigations are also required, but vehicles 

 are unable to conduct this function. 



It is recommended that a program be initiated to provide a concept design for 

 a towed vehicle capable also of maneuvering (freely- swimming or bottom-crawling) 

 and manipulative tasks within an area of at least 50m radius independent of 

 the surface support ship' s movement. The design should - as one option - 

 .attempt to incorporate these features into an existing vehicle such as RUFAS II 

 or DEEP TOW. It would also delineate surface support ship maneuvering requirements 

 and shipboard component and cable requirements needed to accommodate these 

 additional functions. 



