The expectation of poor weather and high sea state, which could greatly 

 complicate locating the MAVA buoy when it surfaced despite its being equipped 

 with two radio beacons and two zenon flashers, led to the decision to sever 

 MAVA below the dual anchor release package. This would permit acoustically 

 tracking the functioning anchor release hanging from the surfaced array. The 

 opportunity to retrieve the anchor releases and perform failure analysis was 

 additional motivation to sever MAVA within 100 meters of the bottom. 



Given the conditions of extreme water depth, poor navigation aids and 

 the expectation of poor weather conditions, it was obvious that the ability 

 to control and position the recovery apparatus was of paramount importance. 



Ill . Moored Sweepline Technique 



The general concept of the moored sweepline technique is shown in 

 figure 2. An acoustically instrumented array, 600 meters long and equipped 

 with cutting grapnels, was anchored on the bottom at a predetermined location 

 near MAVA. The ship then steamed away from the anchor point while cable was 

 being payed out until the sweepline was positioned in a horizontal attitude. 

 A weight (4500 pounds in water) attached to the upper end of the sweepline 

 created the desired taut, horizontal configuration. The ship was then maneu- 

 vered such that the sweepline would pivot about the anchor and intersect 

 MAVA at some point between the anchor and the dual release package. 



Instrumentation of the array with two transponders and a pinger permitted 

 continuous determination of both horizontal position and vertical configuration 

 of the array. A transponder net was deployed in the vicinity of MAVA for this 

 purpose. Details of this instrumentation and its utilization are provided in 

 subsequent sections of this report. 



The controlling factor in successfully performing the sweepline opera- 

 tion was the ability to maneuver the array to the intended anchor point and 

 to control the position of the sweepline in both the horizontal and vertical 

 planes during the sweeping operation. To maximize control of the recovery 

 array during the anchoring phase, the approach was made at a speed of less than 

 one knot, figure 3, and the ship was headed directly into the wind and seas thus 

 minimizing the tendency for the wind to set the ship off course. During the 

 sweeping phase of the operation, the wind (20-25 knots) was used to "sail" the 

 ship around MAVA. 



The recovery operation was conducted from the USNS KANE, a 285 foot 

 long AGS class ship. The KANE is equipped with a trainable bow thruster. 

 The deck machinery used in the recovery operation consisted of a Western Gear 

 traction winch capable of a 30,000 pound line pull and a slack tensioner. The 

 winch was equipped with 12,000 meters of 9/16 inch diameter, 3X19 construction 

 wire rope. 



IV. Design Details - Sweepline Array 



The general layout of the recovery array is shown in figure 4, while de- 

 tails of the construction and hardware are given in figures 5 through 8. 

 Basically, the array consisted of a sweepline stretched between two weights. 

 The lower weight, termed the depressor weight, was a steel cylinder weighing 



