depths down to 2 0, 000 feet, while the Krupp sphere has no 

 depth limits and was the one used for the deep dives off 

 Guam. The essential differences between the two spheres 

 are: (1) the method of assembly and (2) the wall thickness. 

 The Terni sphere consists of two hemispheres that are 

 joined together at a flange. The Krupp sphere is in the 

 form of a central ring with two end caps joined to it. On 

 the Krupp unit the original joint was made with an epoxy 

 glue; however, during one of the dives this joint failed and 

 it became necessary to secure these two sections with a 

 mechanical fastening system. Wall thickness of the Terni 

 sphere is approximately from 3-g- to 6 inches and of the 

 Krupp sphere from 5 to 7 inches. The greatest thickness 

 in both cases occurs at the reinforcement around the 

 window and the entrance hatch. In order to be interchange- 

 able, both spheres have an external diameter of 7 feet 2 

 inches. The steel used in each is a nonfatiguing chrome - 

 nickel-molybdenum alloy which is forged and machined to 

 exact size. Each sphere has two diametrically opposite 

 openings: the primary observation window with the 12 

 hull penetrators arranged around it, and the entrance 

 hatch which is also fitted with a window. The windows 

 are Plexiglas cones laminated to the correct thickness. 

 Access to the sphere is via an entrance tube (antechamber) 

 starting at the top of the float at the conning tower and 

 ending below the float with an elbow that is attached to the 

 sphere. The weight of the Terni sphere is 11 tons while 

 the Krupp sphere weighs 14.25 tons, the additional 3.25 

 tons being the result of the greater wall thickness. 



PRIMARY SYSTEMS 



Electrical 



The primary 24 volt electrical system of TRIESTE is 

 powered by 56 twelve-volt, 48 ampere-hour, lead-acid 

 batteries located in four aluminum saddle tanks fastened 

 to the top of the float beneath the superstructure. Each of 

 the four battery tanks or boxes is pressure-compensated 

 through the use of transformer oil and, therefore, during 

 submergence the batteries themselves are subjected to 

 full depth pressure. 1 Three of the boxes are allotted for 



1 Navy Electronics Laboratory Report 106 3, Evaluation of 

 External Battery Power Supply for Bathyscaph TRIESTE , 

 by L. A. Shumaker, 18 August 1961 



16 



