Feasibility of Pressure Hulls for Ultradeep Running Submarines

Whether the next generation of submarines can operate more deeply depends on the feasibility of developing pressure hull structures sufficiently strong to resist intense external pressure, but also sufficiently light that adequate excess of buoyancy remains over hull weight to accommodate propulsion plant, personnel, and “payload.” By extrapolation of principles of design now employed for shallower running boats, calculations were made of the strength-weight characteristics of structure in the depth range of 2,000 to 20,000 feet. Results indicate that, by utilizing materials such as aluminum alloy 7079-T6, titanium, fiberglas-reinforced-plastic, and superstrength steels, submarine hulls appear feasible for successful operation to depths of one, two, and even three miles, without trade-off sacrifices in speed or combat potency. The yield strength-density ratio of a material serves as its index of efficiency, but cost and ease of fabrication must also be considered in design. Significant problems remain in construction technology that could be mitigated by use of sheathed assemblies wherein nonweldable materials can be effectively employed as hull constituents.