In the DSRV's two 5,564-pound-capacity 

 tanks are used to store water that is pumped 

 out of the mating skirt after it has attached 

 to a stricken submarine; in effect, these 

 tanks work as both positive and negative 

 buoyancy systems although their function- 

 ing is strictly a by-product of the rescue 

 mission. 



ALVIN, in its early design, incorporated 

 nine aluminum (7178-T6) spheres within a 

 syntactic foam (42 pcf) package to provide 

 approximately 4,000 pounds of positive buoy- 

 ancy (Fig. 6.7). To prevent corrosion and 

 stress corrosion, oil surrounded each sphere. 

 The spheres were later discarded and now 

 the entire package consists solely of syntac- 

 tic foam. 

 Collapsible Bags: 



Carried within each sphere of the DSRV 



are four collapsible bags. Prior to a rescue 

 dive, the bags are filled with water to pro- 

 vide 4,080 pounds of negative buoyancy. 

 When the rescuees are aboard the DSRV, the 

 bags are drained into the stricken submarine 

 to compensate for the weight of the rescuees. 



Small Weight Drop: 



A system common to all French and West- 

 inghouse vehicles involves the dropping of 

 small lead weights to incrementally attain 

 positive buoyancy; DEEPSTAR 4000 may 

 serve as an example. Located immediately 

 aft of the pressure sphere 3.4-pound lead 

 weights hang on a notched track trending 

 port-starboard. When the pilot activates the 

 command lever, hydraulic pressure shifts a 

 double-ended piston to one side and rachet 

 fingers attached to a sliding carriage engage 



Fig 6 7 ALVINs original buoyancy package consisled of synlaclic loam and aluminum spheres The total package provided 4.000-lb positive buoyancy (WHOI) 



298 



