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The Swedish Södermanland class of diesel-electric submarines consists of HSwMS Södermanland and HSwMS Östergötland. These two submarines were originally launched as Västergötland-class submarines in 1987 and 1990, and have been relaunched as a new class after extensive modernization in 2003 and 2004 by Kockums AB. The pressure hull had been cut in two after the sail and a 12 m (39 ft 4 in) long new section with an air-independent propulsion system was inserted. It contains two Stirling engines which are coupled to electric generators and heated by burning diesel fuel with liquid oxygen stored in cryogenic tanks. The AIP system can provide electric energy to extend the submarine's submerged time from days to weeks.

HMS Södermanland.jpg
HSwMS Södermanland at sea
Class overview
Name: Södermanland class
Builders: Kockums
Operators:  Swedish Navy
Preceded by: Näcken class
Succeeded by: Gotland class
Planned: 4
Completed: 2
  • HSwMS Södermanland
  • HSwMS Östergötland
General characteristics
Displacement: Submerged: 1,500 t (1,500 long tons; 1,700 short tons)
Length: 60.5 m (198 ft 6 in)
Beam: 6.1 m (20 ft 0 in)
Draft: 5.6 m (18 ft 4 in)
  • 2 × Hedemora Diesel-electric engines
  • 2 × Kockums v4-275R Sterling AIP units
Speed: Submerged: 20 kn (37 km/h; 23 mph)
  • 18 Officers
  • 6 Conscripts
Sensors and
processing systems:
  • 6 × 533 mm (21.0 in) torpedo tubes
  • 3 × 400 mm (15.7 in) torpedo tubes
  • Mines

The class is planned to remain in service until 2019-20 when it will be replaced by the future Blekinge-class submarines.[1]

Two submarines of similar modifications, known as the Archer class are in service with the Republic of Singapore Navy.


Ship name Laid down Launched Commissioned Service Status
Södermanland 12 April 1988 21 April 1989 1st Submarine Flotilla Refitted 2003, Active
Östergötland 9 December 1988 1989 1st Submarine Flotilla Refitted 2004, Active


  1. ^ Karlberg, Lars Anders (12 April 2010). "Tolgfors beställer nya ubåtar och nya helikoptrar" (in Swedish). NyTeknik. Archived from the original on 16 June 2010. Retrieved 4 April 2015.

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