The Sjölejonet class was a series of nine coastal patrol submarines operated by the Swedish Navy during World War II and early Cold War. The boats were developed as part of a Navy modernization program intended to counteract Germany during the late 1930s. The boats were the first indigenous Swedish design, and incorporated unique weapons. During World War II, the boats conducted patrols along the coast to maintain Swedish neutrality. By the start of the Cold War, the vessels were retrofitted before being withdrawn from service by the early 1960s and being replaced by the .
Development and design Throughout the 1930s, Sweden became increasingly concerned regarding German expansionism and greater Nazi influence in the Baltic. As a result, the Riksdag began an initiative to modernize and reformed the military. That decade, the Navy was in the process of replacing World War I-era submarine fleet with new boats. As part of this effort, the Sjölejonet class was intended to be small submarines ideal for patrols along the Swedish coast. The design featured a length of , beam of , and a draught of . They featured a complement of 35 and were propelled by two MAN Diesel engines which produced and two electric motors that produced through two propellers. While surfaced, the submarines had a maximum speed of and a displacement of 580 tons; when submerged, they had a speed of and displacement of 760 tons.
While previous Swedish submarines were based on foreign designs, the Sjölejonet class were the first indigenous designed Swedish submarines. The most unique aspect of the submarines was their armament. They were equipped with six torpedo tubes: three mounted in the bow, one in the stern, and two in remotely-controlled rotating mounts on the deck in a system similar to French submarines. On the deck were also two deck guns on top of disappearing mounts, which was common on Dutch submarines.
Service history Three submarines were initially ordered from Kockums, in Malmö, which were completed by 1939. As tensions increased by the end of the decade, another six were ordered, and were completed by 1942. The submarines were deployed to maintain Swedish neutrality during World War II. On 4 September 1942, Sjöborren collided with a ship and sank, although she was later repaired and brought back into service. In the 1950s, the submarines were refitted: the sail was streamlined, and both the deck guns and deck torpedo tubes were removed. The submarines were stricken between 1959 and 1964, with several names reused on new s in 1964.
Ships in class +DataNameLaid downLaunchedCommissionedStrickenSjölejonet193525 July 193621 September 193815 May 1959Sjöbjörnen 193615 January 193720 March 19381 November 1964Sjöhunden 193726 November 193818 December 19391 July 1960Svärdfisken 193918 May 194026 April 194115 May 1959Tumlaren 19408 September 194019 July 19411 January 1964Dykaren 194017 December 194018 October 19411 December 1959Sjöhästen 194019 October 194016 July 19411 April 1963Sjöormen 19405 April 19413 December 19411 January 1964Sjöborren194114 June 194120 May 194215 June 1959
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