The Gotland class attack submarines of the Swedish Navy are modern diesel-electric submarines. They are the first submarines in the world to feature a Stirling engine air-independent propulsion (AIP) system, which extends their underwater endurance from a few days to weeks.[1] This capability had previously only been available with nuclear powered submarines.
As of 2008 the Gotland-class attack submarine is one of the most modern submarines of the Swedish Navy in service, mainly designed for submarine missions such as anti-shipping operations, ASW-missions, forward surveillance, special operations and mine-laying tasks.[1]
It is a non-nuclear vessel running on an Air Independent Propulsion (AIP) system with low signatures, extreme shock resistance and a powerful combat system. Together with other features this results in a submarine able to carry out the missions listed above.[1]
The auxiliary Stirling engine uses liquid oxygen and diesel fuel to drive 75 kilowatt generators for either propulsion or charging batteries. The AIP endurance of the boats is around 14 days at five knots (9 km/h).
Automation and computerized steering allow a single operator to steer the submarine in depth and course. Only a small crew is required, leading to good accommodation standards and low operating costs[1]
After being refit and upgraded to sustain the higher temperatures of tropical water,[2] HMS Halland took part in a multi-national exercise in the Mediterranean from September 16th 2000. Allegedly, there she remained undetected while still recording many of her friendly adversaries, attracting interest from the participating countries. In early November the same year, she participated in a NATO “blue-water” exercise in the Atlantic. There she reportedly won a victory in a mock “duel” with Spanish naval units, and then the same in similar duel against a French SSN, a nuclear-powered attack submarine. She also “defeated” an American SSN, the USS Houston.[2]
HMS Gotland onboard M/V Eide Transporter in San Diego.
HMS Gotland transits through San Diego Harbor with the Nimitz-class aircraft carrier USS Ronald Reagan (CVN 76) following close behind during the “Sea and Air Parade” held as part of Fleet Week San Diego 2005.In 2004, the Swedish government received a request from the United States of America to lease HMS Gotland – Swedish-flagged, commanded and manned, for a duration of one year for use in anti-submarine warfare exercises. The Swedish government granted this request in October 2004, with both navies signing a memorandum of understanding on March 21, 2005.[3][4] The lease was extended for another 12 months in 2006.[5][6][7] In July 2007, HMS Gotland departed San Diego for Sweden.[8]
HMS Gotland managed to snap several pictures of the USS Ronald Reagan during a wargaming exercise in the Pacific Ocean, effectively “sinking” the aircraft carrier.[9] The exercise was conducted to evaluate the effectiveness of the US Fleet against diesel-electric submarines, which some have noted as severely lacking.