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6.1.5 Diver Assist ROV 



The application of ROVs as diver assist vehicles was quite fortuitous. There 

 was no intent on the part of the designer to conduct the type of diver-assist 

 services which several of the vehicles (particularly the RCV-225) are now 

 providing. Since this type of function will undoubtedly continue, and will 

 probably increase, there is a need for a vehicle designed specifically for 

 diver assistance in the commercial field. 



The first step in this program should involve an analysis of the tasks commercial 

 divers perform to identify the support services required. Aspects of assistance 

 such as: safety, navigation, location, additional electrical, pneumatic and 

 hydraulic power, tooling, emergency breathing air/gas communication (diver-to- sur- 

 face) and supplemental lighting should be, at a minimum, considered in the design. 

 Similar to the NOAA program for a diver assist ROV for scientific use (Section 

 5.3.2), this program should aim at one or, perhaps, several concept designs 

 in areas of support for inspection and maintenance, repair, construction and 

 exploratory drilling. 



5.1.6 Acoustic Imaging 



In many inshore areas and coastal areas, and during various phases of construc- 

 tional/installation, water visibility is so poor that closed cirucit television 

 viewing is impractical. As an alternative an acoustic imaging system is required 

 which can provide picture information of objects of interest under conditions 

 where television is ineffective. 



There are acoustic imaging systems used in various military endeavors and 

 those which are also available commerically (EMI Electronics Ltd. , Surry offers 

 such a system) . These technologies - as far as can be determined - have not 

 been deployed from an ROV. As a first step the commercial systems and, to the 

 degree possible, the military systems, should be evaluated for application 

 from an ROV. The results of these evaluations should be made available to the 

 user community. If the results show the need for improvement, a research 

 and development program should be initiated to provide an instrument which 

 will provide the required resolution and ROV compatibility. 



6.1.7 Heave Compensation 



Towed vehicles (and tethered, free-swimming vehicles in certain modes) are 

 subject to vertical excursions imparted by heave of the surface support ship. 

 The heave imparted can be significant. (According to Dr. F. M. Speiss, Scripps 

 Institute of Oceanography, the vehicle motion can be 1:1 or at least 1^:1 of 

 the ships motion. ) The resultant effects on photography and television viewing 

 are to periodically bring the cameras into and out of focus. 



In one instance, mechanical accumulators aboard the support ship are used to 

 modify the effects of heave. The technique is not entirely satisfactory since 

 the accumulators cause mechanical degradation of the cable. A cable accumulator 

 is required which can be used on or just above the towed vehicle. With this 

 arrangement any degradation of the cable can be corrected by removing several 

 feet from the end. If the fish is lost due to cable failure at the accumulators, 

 then only a few feet of the cable will be lost rather than the entire length. 



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