Västergötland-class

The Västergötland class, designated Type A17, is a series of diesel-electric submarines built by Kockums AB. Development was initiated following a design contract in 1978 and a construction contract in 1981. The class replaced the Draken II class and incorporated design elements from the preceding Sjöormen and Näcken classes. Four vessels were constructed between 1983 and 1988.

The class features a two-deck single-hull design divided into two watertight compartments by a central bulkhead. It utilizes an X-configuration rudder and after hydroplane system. The submarines were designed for multiple roles, including attack, minelaying, surveillance, anti-submarine warfare, and special forces operations. This class introduced increased submarine hunting capacity and the ability to fire multiple wire-guided torpedoes simultaneously against different targets.

The four units in the class are Västergötland, Hälsingland, Södermanland, and Östergötland. The class entered service in 1987. Between 2003 and 2004, Södermanland and Östergötland underwent refits that included the addition of a hull section equipped with Stirling engine air-independent propulsion (AIP). These vessels were subsequently reclassified as the Södermanland class. Östergötland was decommissioned in 2021, leaving Södermanland as the final unit of the class in Swedish service.

The Republic of Singapore Navy purchased Västergötland and Hälsingland in 2005. These vessels were refitted with air-independent propulsion systems and climatisation for operations in tropical waters. They were relaunched in 2009 and 2010 as the Archer class and remain active.