float is drained tiirough valves at the float 

 bottom. The recovery procedure takes about 

 the same time as launching. Some 300,000 

 gallons of gasoline are carried aboard the 

 ARD, and at 19^/gallon , the cost is not 

 insignificant. Some savings are realized, 

 however, because the unused gasoline can be 

 turned back in and used for its original pur- 

 pose. 



Controlling buoyancy when using gasoline 

 is a fulltime job. As the bathyscaph de- 

 scends, the gasoline loses some buoyancy 

 because it is more compi'essible than seawa- 

 ter and the ambient temperature causes it to 

 cool. Consequently, the operator is required 

 to drop shot ballast to compensate for the 

 loss of positive buoyancy. On ascent, the 

 reverse occurs and the operator is required 

 to vent off gasoline to maintain a steady, 



controllable rate of ascent. Piccard (9) de- 

 scribed in detail the complications involved 

 with gasoline as a buoyant source. The con- 

 clusion is easily reached that syntactic foam, 

 in spite of its present high cost, is an ideal 

 replacement for gasoline. 



TRIM SYSTEMS 



The ability to change a submersible's up or 

 down bow angle solves two general opera- 

 tional problems: 1) Instruments or equip- 

 ment may be installed that cause the vehicle 

 to be heavy in the bow or stern; this can be 

 corrected by adding or subtracting weight or 

 displacement at the opposite end, and 2) if a 

 submersible is required to follow an upward 

 or downward sloping bottom, its bow angle 

 may be changed statically so that the vehicle 

 "flies" parallel to the bottom. More special- 



Fig 6 8 ALUMINAUT's crew loading shot ballast at Roosevelt Roads, Puerto Rico (NAVOCEANO) 



301 



