Swedish submarine HSwMS Södermanland has return to service following a lifetime extension

Swedish Submarine Södermanland Re-Launched Following Lifetime Extension
Swedish submarine HSwMS Södermanland has been re-launched following a lifetime extension ordered in 2022.

Submarine HSwMS Södermanland together with three of the newer Gotland-class make up Sweden’s small but potent force of air-independent submarines, and are a key capability for the Swedish Navy as well as for the Swedish Armed Forces as a whole.

Originally built in the late 1980’s as part of the four-strong Västergötland-class of conventional diesel-electric submarines, she and since-mothballed sister HSwMS Östergötland underwent an extensive mid-life update at the start of the millennium. This included lengthening the hull and installing air-independent Stirling-machinery, as well as upgrading a number of sub-systems to give combat capability on par with the more modern Gotland-class. The two other sisters eventually came to undergo a somewhat similar upgrade, as part of being sold to Singapore where they currently serve as the Archer-class.

As part of the original timeline, the HSwMS Södermanland would have been retired by now, but a combination of delays to the Blekinge-class and the increasingly tense security situation following the occupation of Crimea in 2014 and the full-scale invasion of Ukraine in 2022 has seen an increased focus on the Swedish submarine fleet, with a decision to give all three of the Gotland-class vessels a mid-life update (as opposed to the originally planned two), as well as the decision to extend the lifespan of the HSwMS Södermanland, allowing it to serve up to 2030.

The details of the lifetime extension program have not been made public. Saab in their press release following the re-launching of the vessel at their shipyard in Karlskrona described it as including “modifications, capability enhancements and extensive overhaul.” However, the original press release by the Swedish Defence Material Administration, FMV, back in 2022 when the order was placed used a more careful wording, which seemed to point to the scope largely being centred on avoiding obsolescence issues and general deep maintenance requirements. The only detail mentioned by FMV was the acquisition of new batteries as well as related research, which was included in the total contract sum of 470 million SEK (approximately 41 million EUR).

HSwMS Södermanland (Saab photo)
Based on this, the fitting of systems and sensors associated with the Blekinge-class program, a key feature of the ongoing MLU of the Gotland-class submarines, seems unlikely. Still, even with only minor capability improvements, HSwMS Södermanland remain a very capable vessel. This is particularly true in the confined waters of the Baltic Sea, where her small size as well as sensors and weapons developed for littoral conditions provide her with key advantages compared to many other submarines.

However, with availability being a key need considering the size of the small Swedish submarine force it appears clear from the FMV release that the actions taken will address the typical issues of ageing platforms such as obsolescent sub-systems with difficult to source spares and increased unscheduled downtime due to more frequent breakdowns. As such, the HSwMS Södermanland will have had a career spanning more than forty years by the time of her eventual retirement.

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