Stockholm-class corvette

Stockholm class corvette is a corvette class in the Swedish Navy. Built in Karlskrona 1984–1985, it is armed with eight RBS15 anti-ship missiles, torpedoes, one 57mm cannon and several machine guns. In 1999/2000 the two units in the class were upgraded in the Karlskrona shipyard Kockums. The upgrade included new engines, sensors, stealth technology, and navigation systems, the goal being to bring the technology up to the same level as the Visby class.

History
The Stockholm Class Corvette started as a study for a ship with increased endurance, a project called Ytattack-81 (Surface combatant-81), which was built on the torpedo boats of Spica and Spica II class, but with an increased displacement from 230 tons to 350 tons. The engine was to be a CODAG-concept, two diesels and one gas turbine. However, the class looked to become just another desktop project.

In the early 1980s a series of submarine incidents occurred within Swedish territorial waters, the most famous of which was U 137 which ran aground outside Karlskrona 1981. These incidents showed that the Swedish Navy was seriously lacking in its anti-submarine (ASW) capacity. Specifically, it needed new hulls designed to anti-submarine warfare, and it needed them fast. The decision was to use the Ytattack-81 project and modify it for ASW operations, as designing a completely new ship is a time-consuming and costly task. It was given a towed array sonar, ASW torpedoes and the ELMA anti-submarine grenade launcher system. HMS Stockholm was launched 22 August 1984 closely followed by HMS Malmö 23 March 1985, both ships entered service 1 May 1986.

In the middle of the 1990s the ships started to show their age, mainly because of their high mileage and the latest few years explosive development of electronics. The Stockholm class was a successful design and the ships' basic status was good despite a hard life so the Swedish Defence Administration decided to give the ships a second life. HMS Malmö was the first to be modernised in 1999 with HMS Stockholm following suit 2000. The modernisation included new engines, combat control systems, fire control systems, SIGINT and navigational systems. The ships both went through extensive modification of the mast, hull and superstructure to reduce their radar cross-section. Much of the modification was also made with low maintenance in mind to minimise the need for expensive repairs in the future. The guiding principle for the project was to update as much of the systems as possible to the same level as the Visby Corvettes. Both ships are back in operational condition now, attached to the 31'st Corvette Division of the 3rd Naval Warfare Flotilla.

In early 2009 the Swedish government decided that the two ships in the class was to join the EU-lead taskforce outside Somalia, where its would fight piracy. In May 2009 the ships started their first patrol outside the Somalian coast. On May 26 HMS Malmö responded to a pirate attack on the Greek ship M/V Antonis. The Corvette fired warning shots with its 57mm canon and arrested seven pirates.