Saab Relaunches Swedish Navy Attack Submarine HSwMS Gotland After the Mid-Life Upgrade

Saab has relaunched HSwMS Gotland (Gtd), the lead vessel of the Gotland-class of diesel-electric AIP attack submarines in service with the Swedish Navy, after the completion of the Mid-Life Upgrade (MLU).

The relaunch ceremony took place at the Saab Kockums’ shipyard in Karlskrona, Sweden on June 20, 2018.

“The relaunch of Gotland is an important milestone in the evolutionary development of Swedish submarines. After a comprehensive upgrade, integrating the latest generation of important systems such as the Stirling engine, modern sensors and new management functions, Gotland is almost a new submarine, ready to take on missions around the world,” says Gunnar Wieslander, Senior Vice President, head of Saab Kockums.

Submarines are designed to operate for decades in challenging environments whilst remaining adaptable to the tide of technology and future threats. To keep them cutting-edge of technology, Sweden’s Gotland-class submarines have received regular overhauls and upgrades along their operational life.

In 2015, Sweden’s Defense Material Administration (FMV) signed a contract with Saab Kockums which included the mid-life upgrade of two members of the Gotland class, HSwMS Gotland and HSwMS Halland (Hnd), for SEK 2.1 million. The FMV has also asked for option prices for upgrades to HSwMS Uppland, the third vessel of the class.

The contract included the modifications the of two submarines, verification including Set to Work (STW), Harbour Acceptance Test (HAT), Sea Acceptance Test (SAT), training, documentation, spares and upgrade of land-based Training Facility.

For the upgrade, the submarine was cut open in the mid-tank section for adding a new section including sea water cooling, fresh water cooling and water chiller units. The mid-life modification also consisted of upgrades of onboard systems and technology, sustaining the submarine’s operability, and ensuring service to Sweden beyond 2025.

The upgrade process entails many important systems, such as the Stirling Air Independent Propulsion (Stirling AIP MkIII). Sensors and management system are replaced with updated versions. Even the traditional optical periscope is replaced with a new optronic mast.

This updated version of the Gotland will pave the way for the most modern AIP submarine under production today: the A26 for the Royal Swedish Navy. More than 20 systems on-board the new Gotland-class will be implemented in the A26. The MLU therefore contributes to the test and qualification of some of the innovative solutions to be implemented in the future Swedish A26 submarine class.

Gotland is expected to return to the FMV in late 2018 and Halland in late 2019, following the series of platform and combat systems upgrades.

HSwMS Gotland was designed and built by Kockums in Malmö, Sweden and was launched on 2 February 1995, and was subsequently commissioned in April 1996.

Gotland-class diesel-electric submarines 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. This capability had previously only been available with nuclear-powered submarines. The Stirling engines use liquid oxygen and diesel as the propellant.

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