The Swedish Navy’s Gotland-class submarine HSwMS Gotland has started sea trials at Saab shipyard in Karlskrona.

The sea trials have begun following completion of the vessel’s comprehensive mid-life upgrade (MLU) that would ensure the operational service of the submarine beyond 2025.

Saab Kockums Business Area head senior vice-president Gunnar Wieslander said: “The sea trials mark an important phase in the MLU project.

“This is the first time the crew will be able to operate the new systems in the true environment. After extensive training in the land-based training facility, they will now be able to see the true potential of their submarine.”

HSwMS Gotland is the first of two Swedish Navy submarines being overhauled and retrofitted under the MLU.

“This is the first time the crew will be able to operate the new systems in the true environment.”

This will enable the vessels to maintain an operational capability to meet future naval challenges.

The modification involves modernisation of on-board systems and technology, as well as a number of critical systems such as the Stirling Air Independent Propulsion (AIP) for longer duration underwater and the combat system.

In addition, the traditional optical periscope has been replaced with a new optronic mast for enhanced surveillance.

The submarine MLU contributes to the test and qualification of some of the new solutions created to be implemented in future A26 vessels.

More than 20 systems installed on the overhauled Gotland-class ship will be implemented in the new A26 submarine for the Swedish Navy.

Following tests and verifications, the upgraded HSwMS Gotland will be delivered back to the Swedish Navy.