In the early Cold War, the Swedish Navy was one of the most powerful in the Baltic Sea as other regional powers slowly rebuilt from World War II. By 1960, the numerical superiority was lost and a new approach was needed. In response, the Defense Act of 1958 introduced the concept of a "light navy". Compared to the old navy that was built around capital ships, the doctrine emphasized escorts to protect the Swedish coast, with large torpedo boats slated to both serve in task forces with destroyers and operate independently.[1]: 443 An order for such vessels was placed in the early 1950s from Lürssen Werft, a German shipyard that specialized in E-boats during the war. Compared to contemporary torpedo boats, the design featured a much larger and robust hull, which allowed for more weapons and electronics onboard.[2]: 44 [3]: 121
A prototype, Perseus, was laid down in 1950 and featured a standard displacement of 145 tons with two diesel engines, 4 torpedo tubes, a gas turbine, and was later rebuilt as a test bed for further torpedo boat designs. The class featured a waterline length of 45.19 metres (148 ft 3 in), overall length of 48.01 metres (157 ft 6 in), beam of 5.87 metres (19 ft 3 in), and draught of 1.60 metres (5 ft 3 in). They were powered by three MTU V20 diesel engines, which produced 9,000 brake horsepower (6,700 kW) and a top speed of 37.5 knots (69.5 km/h; 43.2 mph). At a cruising speed of 30 knots (56 km/h; 35 mph), the ships had a range of 600 nautical miles (1,100 km; 690 mi). They were armed with six 533 mm (21.0 in) torpedo tubes, two 40 mm (1.6 in) gun (two single mounts), and four 103 mm (4.1 in) and twelve 57 mm (2.2 in) illumination flare launchers. At a standard load, the vessels displaced 155 tons and 170 tons fully loaded. They were crewed by 33 sailors. If the torpedo tubes were removed, they could be fitted with minesweeping equipment.[1]: 449
Many features of the design was retained in the later Spica-class torpedo boats, with the main changes regarding improved fire control.[2]: 44 The design was Lürssen Werft's first fast attack craft design since World War II, and it served as the basis for the Jaguar and Seeadler-class fast attack craft built for the West German Navy.[3]: 121
The vessels were built in two batches at the Karlskrona Navy Yard. The first batch of six were laid down between 1953 and 1954 were commissioned in either 1954 or 1955 while the second batch was laid down between 1956 or 1957 and entered service between 1956 and 1958. Most of the ships were stricken in 1977, but two, Aldebaran and Astrea, remained in service until 1981.[1]: 449
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Swedish Navy