there had been no opportunity to practice. The T-426 was struggling 

 to hold the YC-1378 on station while the Panulirus was attempting to 

 hold the Pontoon Barge stern to the signal cable at Station 1. Once 

 the Inner Mooring Assembly was attached to the bridle and the 

 Inner Coral Hook was slipped off, it was possible to pay out some 

 cable from the large braked drum to get the signal cable well below 

 the surface where it could not be damaged. We achieved this 

 situation at 1700 hours. 



Fig. 5-16 is a scale drawing which shows the sequence of operations 

 involved in laying the Signal Cable /Sensor Array and setting the 

 Inner Mooring. The geometric situation at 1700 hours, just described, 

 is shown as Stage 1 in the drawing. Both barges moved inshore 

 while paying out cable until Station 1 was 1200 ft. from the Pontoon 

 Barge and 4100 ft. from the YC-1378. At this time (1835 hours, 

 Sta^ 2) the cable drums were stopped and a geometry check was 

 made. At this and later stages the geometry check was made on a 

 large scale plot of the cable geometry as determined from two sources: 



(1) a graphical construction based upon the known positions of the 

 barges and Outer Coral Hooks and the known cable lengths, and 



(2) a determination of Station 2 and Station 4 depth from their 

 pressure transducer signals. The tension transducer provided an 

 overall reasonableness check and a warning of potential overstress. 

 Note that all the array sensors were interrogated and recorded 

 during the entire operation by means of the Backup Data Acquisition 

 System. This System, shown in Fig. 5-17, consisted of a digital 

 ohmmeter, printer, and sequencing electronics. 



Next the barges moved up to Stage 3 and another geometry 

 check was made. From this point on the YC-1378 merely held 

 station and braked the cable drum with 4100 ft. of cable out to 

 Station 1. The Pontoon Barge was then required to hold station 

 only approximately by visual reference to the angle of the Inner 

 Mooring Cable and the line between the YC-1378 and St. Davids 

 Lighthouse. The Pontoon Barge then lowered the Inner Coral Hook 

 another 600 ft. to achieve Stage 4. 



At Stage 4 the Inner Coral Hook was known to be within 200 ft. 

 of the bottom. The YC-1378 position had been chosen so that, 

 after Stage 4, the array between Stations 1 and 4 would translate 

 parallel to itself while the Inner Coral Hook was lowered to the 

 bottom. In this way, whenever the Inner Coral Hook grounded, 

 establishing Stage 5, the array would pitch up to the horizontal 

 attitude (Stage 6) as the tensile load was transferred from the 

 YC-1378 barge to the Inner Coral Hook. At 2137 hours the coral 

 hook grounded. We immediately reduced throttle on the T-426, 

 permitting the YC-1378 to slip seaward while transferring the load 



231 



