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SIGMA-class corvettes are designed and built by Damen Schelde Naval Shipbuilding, a company based in the Netherlands, for the Indonesian Navy (TNI-AL). Four 9113 Sigma-class corvettes were delivered to TNI-AL between 2007 and 2009.
Advanced propulsion system and good sea keeping capabilities make the Sigma-class corvettes suitable for conducting operations in the Indonesian territorial waters. The corvettes can be deployed in maritime search-and-rescue (SAR), exclusive economic zone (EEZ) patrol and anti-submarine warfare (ASW) missions.
Ship integrated geometrical modularity approach (SIGMA) concept
The SIGMA-class corvettes of the Indonesian Navy were built around the concept of ship integrated geometrical modularity approach (SIGMA), which provides the user with high flexibility at reduced costs by allowing modularity in design.
The corvettes have an overall length of 90.71m, beam of 13.02m and draft of 3.60m. Each corvette has a displacement of 1,700t and can accommodate a crew of 80.
SIGMA-class corvette construction
The keel for the first corvette in class, KRI Diponegoro (365), was laid down in March 2005. The vessel was launched in September 2006 and commissioned in July 2007.
SIGMA Class frigates are built by Damen Schelde Naval Shipbuilding for the Royal Moroccan Navy.
The second corvette, KRI Hasanuddin (366), was also laid in March 2005 and launched in September 2006, but commissioned in 24 November 2007.
KRI Sultan Iskandar Muda (367), the third corvette, was laid in May 2006 and launched in November 2007. It was commissioned in October 2008.
Laid in May 2006, the fourth and last corvette, KRI Frans Kaisiepo (368), was launched in June 2008 and commissioned in March 2009.
Weapon systems fitted to the Indonesian corvettes
The SIGMA-class corvettes are equipped with MBDA Mistral Exocet surface-to-surface missiles (SSMs) and Tetral surface-to-air missiles (SAMs).
The Oto Melara 76mm super rapid gun fitted at forward can fire at a rate of 120 rounds a minute. Two 20mm G12 Denel Vector guns mounted aboard the vessel provide defence against aerial threats.
The corvettes are also equipped with two standard deck-mounted B515 trainable triple-barrel launchers, which are an upgraded version of the former ILAS-3 torpedo launcher.
Sensors / radars aboard the corvettes
Thales was awarded multiple contracts valued at approximately €60m for the delivery of above water and under water defence systems as well as communication systems for the first two corvettes, in 2004.
Kingklip medium frequency hull-mounted sonar gives the corvettes submarine detection capability. The LIROD Mk2 radar aboard the corvette serves as a fire control radar and optronic director, while MW08 3D multibeam radar operating in the G-band (C-band) provides surveillance and target designation.
The TACTICOS combat management system (CMS) from Thales serves as a command-and-control system which integrates onboard sensors.
Helicopter handling capabilities
The aft helicopter deck of the SIGMA-class can handle helicopters with a maximum weight of 5t. Provided with lashing points and refuelling system, the heli-deck enables day and night operations.
In addition to two Terma SKWS (soft kill weapon system) decoy launchers, the corvettes are fitted with Thales DR3000 ESM system and Racal Scorpion 2L ECM system that offer electronic countermeasures.
Propulsion and power
The SIGMA-class corvettes are powered by two SEMT Pielstick diesel engines driving two controllable pitch propellers via two shafts. Each engine delivers a maximum power output of 8,910kW, while the propulsion system provides a maximum speed of 28kt and a range of 3,000nm at 18kt speed. The corvettes also integrate passive roll stabilisation system.
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