The marriage of the nuclear propulsion system of NAUTILUS with the 

 hydrodynamically ideal hull shape of ALBACORE comprised a combination 

 which could be exploited in producing a true submersible. Developments 

 in hull structural materials also permitted operations at greater depths. 

 These three major breakthroughs have led to the design and construction 

 of two types of underwater ships: one, attack submarines of the SKIPJACK 

 (SSN-585) class shown in Figure 5; and two, the strategic underwater 

 deterrent system represented by the POLARIS missile-launching sub- 

 marine shown in Figure 6. A more complete discussion of the various 

 hull shapes may be found in Reference 2. 



More recent developments, primarily in the area of structural analy- 

 sis, and greater confidence in the use of the current hull structural mate- 

 rial (HY-80), which is a high- strength, low-carbon, quenched and temper- 

 ed martensitic steel with a nominal yield strength of 80,000 psi, have led 

 to the design and initiation of construction of the DOLPHIN {AGSS-555), 

 which is a deep-depth experimental submarine. Although this design rep- 

 resents a major increase in depth capability, it also signifies that practi- 

 cally every last bit of strength potential offered by this steel for hull 

 structures of submersibles ^as been exploited. 



In the strength analysis of submarine hulls, the most important 

 element of structure, isolated from an otherwise complex structural 

 system, is the ring- stiffened cylindrical shell. Conical transition sections 



8 



