81 



-Observation and confirmation of attitude of the MC after touchdown 



including visual close inspection of MC base skirt penetration into 



sea floor around the complete perimeter. 

 -Observation and confirmation of release of the lowering bridle including 



visual check of each sling at release. 

 -Visual observation and confirmation of release of the hydraulic umbilical 



from the MC. 

 -Visual observation and confirmation of hydraulically operated flood 



valves to allow final flood-down during ballasting and to insure that 



valves were closed when ballasting was complete. 



A further application of an RCV-225 by Taylor Diving during installation of the 

 Cognac platform's Jacket Base Section (JBS) was described by Michel (1978). 

 Similar to the Martech work described above, Taylor Diving's role was not 

 restricted to only monitoring during this installation; survey and diver assist 

 tasks were conducted also,- these are discussed in subsequent sections. The 

 RCV's role during installation of the JBS was to follow it as it was lowered 

 to the bottom and check its depth, attitude and orientation. A visual study 

 was performed to determine sea floor impact. The RCV was first "flown" (guided 

 through the water) around the bottom of the JBS to determine sea floor penetration. 

 A second check was made by setting the RCV down on top of each leg and using 

 depth readings from the RCV's on-board pressure transducer to determine how 

 level the structure was. Electronic sensors on the JBS transmitted all of 

 this data to the control room. The RCV's task was to verify JBS readings. 

 In one case an electrical umbilical carrying JBS data malfunctioned. The RCV 

 served as an alternate source of information. 



3.1.2.C Cable Installation (Gaudillere, 1978) 



A major factor during cable installation (or flexible pipes) is to synchronize 

 the speed of the lay barge with the speed of the winch from which the cable is reeled. 

 If the winch is too slow excess tension is created which can damage the cabling; 

 if it is too fast, excess cable is laid which can make loops which may turn 

 into kinks which cause difficulty during subsequent burial operations. SESAM 

 employed the RCV-225 from the cable lay vessel to monitor the touchdown point. 

 By providing TV monitors on the bridge and for the winch operator, coordin- 

 ation between ship and winch speed was made possible for a smooth and 

 uniform cable lay. 



3.1.2.d Pipeline Pull-in Procedures (Gaudillere, 1978) 



SESAM has used the RCV-225 to observe pipe pull-ins through "J" tubes and tunnels. 

 The vehicle observes the pulling cable and approach of the pulling head. 

 This permits careful monitoring of the re-entry pipe, and the stopper clamped 

 on it can be stopped within 2cm (1 in.) of a pre-determined position thereby 

 avoiding excess pull and its consequent damage. 



3.1.2.e Pipeline Weighting (Gaudillere, 1978) 



Pipes may be buried or anchored on the seabed by concrete blocks. A large 

 quantity of these blocks have been installed in the Frigg Field, where SESAT-l's • 

 RCV-225 has been employed. The blocks, weighing from 10 to 20 tons, are lowered 



