From the early 1940s to
the ultimate collapse of the USSR, the Soviet Navy pushed its submarine
design bureaus to develop submarines specifically for troop and cargo
transport. While many of these "submarine LST" concepts were not
pursued, the effort offers a fascinating look at the technical
challenges and strategic thought inherent in modern submarine design.
Six variants of Project 748 were developed with surface displacements from 8,000 to 11,000 tons. Most variants had three separate, cylindrical pressure hulls side-by-side, encased in a single outer hull. The first variant met the basic TTE; the second variant carried a larger number of PT-76 amphibious tanks; the third variant had VAU-6 auxiliary nuclear power plants; the fourth variant had two OK-300 reactor plants generating 30,000 horsepower; the fifth variant had the VAU-6 system with a single pressure hull; and in the sixth variant the OK-300 plant was replaced by four VAU-6 units.
This large submarine could carry up to 20 amphibious tanks and BTR-60P armored personnel carriers, and up to 470 troops. In addition to a torpedo armament of four bow 21-inch torpedo tubes with 18 to 20 torpedoes, the submarine was to be fitted with anti-aircraft guns and surface-to-air missiles. And, of course, the submarine could serve as a minelayer.
TsKB-16 recommended proceeding with the fourth (nuclear-propelled) variant. Still, construction was not initiated because the Navy, Ministry of Shipbuilding Industry, and General Staff of the Armed Forces ordered a review of the features of Projects 632, 648, 664, and 748 in an effort to develop a "ubiquitous" or all-capable nuclear submarine. TsKB-16 (now named Volna) was directed to develop a preliminary design for the submarine designated Project 717. More
Cold War Submarines: The Design and Construction of U.S. and Soviet Submarines by Norman Polmar and Kenneth J Moore, Brassy's, Inc., 2004