and 220 metars above the bottom. The minimum distance from the sweepline to 

 MAVA was 280 meters. The ship was then maneuvered to begin the sweeping 

 operation. Contact of the sweepline with MAVA was made at 1850 hours. At 

 that time the sentinel was 580 meters from the sweepline anchor and 105 meters 

 above the bottom. Total line out was 5190 meters. Figure 22 illustates the 

 above sweepline configurations. 



Inspection of the catenary plots indicated that the intersection of 

 the sweepline with MAVA occurred very close to the midpoint of the 100 meter 

 cable between the MAVA anchor and dual release package. Furthermore, the 

 catenary analysis indicated a theoretical static line tension of 11,500 pounds. 

 The distance between the ship and anchor point was limited to 2000 meters 

 during the sweeping operation to keep line tensions at or below this value. 

 It was feared that with the addition of dynamic loading caused by fifteen 

 foot seas, the 23,000 pound elastic limit of the wire rope could be exceeded. 

 The lack of tension data was aggravated by the fact that the cable slack 

 tensioner had developed a leak and vms inoperative. 



It was hoped that MAVA would be cut free by the action of the 9/16 

 inch diameter sweepline chafing against the 1/4 inch diameter MAVA mooring 

 line. At 2155 hours, after three hours of sweepline contact with MAVA and a 

 180 degree sweep, there was no indication that this had occurred. The decision 

 was made to fire the lower anchor release which held the sweepline to the 

 "Bruce" anchor. The sentinel was observed to move rapidly following the 

 release from the anchor. At 2258 hours, one hour and three minutes later, 

 M.AVA surfaced. The surfacing was announced by a shipboard radio receiver 

 which picked up the signal from the radio transponder on the MAVA buoy. 



Subsequent inspection of the MAVA dual release package showed that the 

 h inch diameter cable had been severed by one of the grapnels directly below 

 the Nicopress sleeves at the attachment point. Apparently, the grapnel had 

 moved up the wire rope and lodged at that point. 



VIII. Acoustic Release Failure Analysis 



A failure analysis was conducted on the recovered MAVA anchor releases 

 with the following conclusions. One release failed to operate in either the 

 transpond mode or the command release mode because the connector between the 

 transducer and the electronics had come loose. All connectors of this type 

 have been modified to provide a positive locking feature. The second release, 

 while functioning in the transpond mode would not release upon command. The 

 failure was attributed to a faulty squib. Gun oil, used to clean the firing 

 chamber, had worked its way into the propel 1 ant thus causing the failure. 



IX. Conclusions 



The moored sweepline technique described above worked exceptionally 

 well considering the depth of water, sea state and wind speed. Control of the 

 array during anchoring and sweeping phases was not overly difficult. 



Throughout the operation, theoretical indications and actual experience 

 agreed very closely. 



15 



