23-1. In World War II the capacity of our submarines to survive intense underwater explosive attacks without receiving damage of serious nature was clearly established and continuously increased during the course of the war. This was accomplished principally by instituting a comprehensive shock protection program for all submarines in service and under construction and by increasing the scantlings of the pressure hulls on more recent classes to permit greater operating depths. Section XXIII
Conclusion23-2. The damage experiences of Kingfish, Tunny, Salmon, Scamp, Halibut and Redfish represent instances where considerable permanent pressure hull deformation was sustained by submarines on which all or a substantial portion of the shock protection program had been accomplished. On these vessels, vital equipment was in general not affected seriously although further improvement in the resistance to damage of certain components, particularly piping and electrical items, was clearly indicated.
23-3. From the standpoint of vulnerability to non-contact underwater explosive attack, the ideal submarine is one having a pressure hull of maximum efficiency for the allowable weight of the shell and framing. free of stress raisers, and with all other equipment, appurtenances, systems, etc., of such strength or so well protected from shock that the hull itself will be destroyed before other vital components sustain serious damage. In other words, the ideal submarine could only be destroyed by causing collapse or holing of its pressure hull. This desirable condition has been closely approached on modern U.S. submarines. It is significant to note that only five reports in the entire Japanese list of 468 "positive" sinkings of U.S. submarines referred to in Appendix II mention partial or complete surfacing of a submarine having occurred while it was under attack, none of which can be related to a known sinking, whereas over 200 reports contain mention of sighting large quantities of oil, frequently accompanied by air bubbles and debris, after attacking purported submarines. These figures, although admittedly based on incomplete information, would seem to indicate that destruction of our submarines occurred through rupture of their pressure hulls since it is reasonable to assume that even though a submarine were disabled so that it could no longer operate submerged, sufficient air should remain to permit surfacing.
23-4. In the final analysis, it is apparent that the survival of many of our submarines after receiving war damage was due in very large part to the damage control efforts of their personnel. The long standing requirement that all hands in the submarine service know their ships thoroughly has paid priceless dividends in terms of human life and the successful prosecution of the war.
23-5. As a result of the great improvements made in anti-submarine warfare during the past few years and prospective radically new developments in propulsion machinery, the concept of the submarine of the foreseeable future has undergone drastic change. U.S. submarines as developed for World War II were designed primarily for employment as submersible surface raiders with high surface speed and low submerged speed. This type of submarine was remarkably successful in operations against the Japanese and fortunately suffered a relatively low rate of attrition due to the marked ineffectiveness of the enemy anti-submarine effort. The present trend of U.S. submarine design is in the direction of smaller, high submerged speed attack submarines capable of operating at extreme depths. Other types of submarines for special missions are also under consideration. With the advent of a suitable propulsion plant capable of delivering great power for sustained operations submerged, the submarine will become a true submersible.
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