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maintain the position of the tether cable below the workboat and will 

 allow the TMV to operate awa'y from the cable depressor without the 

 danger of the tether cable becoming entangled in the riser. The 

 TMV, cable depressor, and payload will be maneuvered to the desired 

 depth; then the TMV s propulsion system will move the system hori- 

 zontally until the tool package can attach to the riser. In this 

 mode, the variable buoyancy system will be used to compensate for 

 changes in payload, such as releasing a replacement production hose 

 after it has been connected. 



When operating in the suspended mode, the TMV will be suspended from 

 the launch and recovery system's heave compensator by the tether 

 cable. Since the TMV itself will be neutrally buoyant, the load 

 on the tether cable will only be the payload weight plus the TMV 

 dynamic loads (which will be minimized by the heave compensator) . 

 The TMV and payload will be lowered to the desired depth where the 

 TMV's propulsion system will move the system horizontally until 

 the tool package can attach to the riser. The maximum in-water payload 

 for this mode is 4,762kg." 



Current plans include continued development of the TMV to fabrication and 

 testing. Testing of the launch/retrieval system and general purpose tool 

 package will follow. Extensive offshore tests are planned to prove the systems 

 effectiveness before it is employed on an actual riser maintenance mission. 



