page_title: Soviet S-class submarine
section_title: IX series
hierarchical_section_title: Soviet S-class submarine / Technical description / IX series
caption_attribution_description: English: soviet submarine S-1 at sea trials. Without 100 mm gun Русский: советская субмарина С-1 на морских испытаниях. 100 мм орудие ещё не установлено
context_page_description: The S-class or Srednyaya submarines were part of the Soviet Navy's underwater fleet during World War II. Unofficially nicknamed Stalinets, boats of this class were the most successful and achieved the most significant victories among all Soviet submarines. In all, they sank 82,770 gross register tons of merchant shipping and seven warships, which accounts for about one-third of all tonnage sunk by Soviet submarines during the war.
context_section_description: Only three ships were built in this group, S-1, S-2 and S-3, using partially German-supplied machinery. The boats were of semi-double hull type, with riveted pressure hull and welded light hull sections in the superstructure and extremities for improved seaworthiness. The sail was medium-sized and oval in plane, to reduce water drag. It housed the conning tower, the bridge, periscope fairings and a 45 mm (1.77 in) anti-aircraft gun. A net cutter was fitted atop the bow. The hull was separated into seven compartments, three of which were able to withstand 10 atm pressure. Nine main ballast tanks, separated into three groups (4 bow, 2 stern, 3 midships), together with a balancing tank and a quick dive tank were placed in the light hull. Trimming tanks were inside the pressure hull. Ballast tanks were emptied by pressurized air or engines exhaust, thus removing the need for ballast pumps.
  The boats were powered by two MAN М6V49/48 four-stroke atmospheric reversive diesels (2000 hp each at 465 rev/min) that drove two fixed pitch propellers together with two Electrosila PG-72/35 electric motors (550 hp at 275 rev/min), connecting by BAMAG (Berlin-Anhaltische Maschinenbau AG) type friction clutches. Delivery of the engines for the third boat was constantly delayed and eventually it was equipped with domestically produced ones. For underwater propulsion energy was supplied by 124 APA 38-MAK-760 accumulators, equipped with K-5 hydrogen burners. The batteries lacked the traditional central walkway, instead using special service trolleys suspended from the deckhead. This design significantly decreased the height of the battery compartment, freeing space for the crew. The electrical system omitted the complicated layout common on earlier Soviet designs, and was simple and reliable. All connections were insulated and the bulkhead feedthroughs were designed to withstand the same pressure as the bulkheads themselves. It had better maneuverability than other smaller Soviet, German, British and Italian submarines (e.g. the British U-class submarines, the German Type VII submarines and the Italian Acciaio-class submarine).
  The vessels were equipped with six torpedo tubes (four bow and two stern) of 533 mm (21 in) caliber. Six spare torpedoes could be stored in the racks of the bow torpedo compartment, so the complete load was 12 torpedoes. Usually 53-38 torpedoes were used, as the high-speed 53-39 torpedoes were available only in limited numbers, and the electric ET-80 torpedoes were unreliable and the crews did not like them. It was also possible to launch mines through the torpedo tubes. No torpedo automation was installed, and all shooting was manual. The stern tubes had an interesting feature: instead of the usual doors, they were closed by a special rotating cylinder that streamlined the contour of the stern when the tubes were not in use. A 45 mm (1.77 in) semi-automatic anti-aircraft gun was mounted on the conning tower, and a 100 mm (3.9 in) gun on the deck for surface combat.
  Observation and communication equipment was somewhat less than top-level, but generally adequate. The boats were equipped with two periscopes, observation PZ-7.5 and targeting PA-7.5, mounted very close to each other and reports existed of difficulties in using them simultaneously. Several radios were installed. The Mars-12 microphone system was primary an underwater sensor, and an underwater communication system was also installed on all boats. No radars were installed on any series of the type.
caption: Sea trials of S-1. Protection of artillery is clearly visible. Artillery itself had not yet mounted.
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