ular importance in making recovery plans was whether ALVIN's sail hatch was open or closed, 

 and if closed, whether it could be opened. Although MIZAR had previously located and photo- 

 graphed ALVIN in June 1969, and the pictures showed ALVIN's sail hatch open, it could not 

 be determined if the pressure hatch was open. 



SUPSALV's detailed plan for recovering ALVIN consisted basically of the following 

 steps: 



1. Relocating and marking 



2. Attachment of Hft Hne 



3. Lift to surface 



4. Diver survey and attachment of safety lines 



5. Tow to shallow water 



6. Final lift and salvage. 



1. Relocating and Marking. MIZAR would return to the site where she had located 

 ALVIN in June 1969, relocate ALVIN, drop a transponder to mark datura, and then pro- 

 ceed to Boston Naval Shipyard for outfitting. Upon receipt of a favorable weather fore- 

 cast, the ships, with ALUMINAUT under tow by her support ship, would get underway for 

 the recovery site. MIZAR would return to the site, position herself over ALVIN using the 

 transponder as reference, and maintain station. 



Upon arrival on-site, ALUMINAUT would receive the lift line, lifting bridle with attaching 

 devices, an AMF transponder, and a hatch opening device. The lift line, wound on a reel, would 

 be mounted on special brackets mounted on ALUMINAUT's bow. 



ALUMINAUT would make a test dive to check out all systems. If all was satisfactory, 

 she would continue her descent. MIZAR would interrogate the AMF transponders on the 

 bottom and on ALUMINAUT using a frequency of 16 kHz, and both transponders would 

 answer on 10 kHz. Utilizing a tracking computer, the tracking and plotting team would vec- 

 tor ALUMINAUT to the transponders. Once ALUMINAUT was on the bottom, it was planned 

 that she would use her Straza sonar to interrogate and home in on a CTFM transponder with a 

 maximum range of 800 yards. ALUMINAUT's CTFM sonar should acquire ALVIN at 500 

 yards. STAGEY TIDE would also track ALUMINAUT. 



If the computer did not work, an alternative action would be taken. A second AMF 

 transponder would be put down at a known position relative to the first transponder and, by 

 use of a multiple-range system, the tracking team would be able to compute MIZAR's position 

 relative to the bottom markers. The tracking team would then conn ALUMINAUT to the 

 first transponder until ALUMINAUT acquired the CTFM transponder. ALUMINAUT, when 

 within 500 yards of ALVIN, should then have both ALVIN and the first transponder acquired 



