Sigma-class corvette

The Sigma class corvette is a corvette or frigate with ocean capabilities.

Modular design
The basic design of the Sigma Patrol Series can vary as the hull segments are designed as components. Ships can vary in the number of hull segments and in the order in which they are placed. Sigma stands for Ship Integrated Geometrical Modularity Approach. The ship's main dimensions are named in the types itself, SIGMA 9113 stands for 91 meters long and 13 meters wide, same is with the SIGMA 10513, 105 meters in length and 13 meters wide.

The design was derived from the earlier High Speed Displacement hull form by MARIN Teknikk AS in the 1970s.

Users

 * Indonesia has four 9113 class corvettes in active service by 2009 and in August 2010 has signed a deal to build frigate PKR 105 based on SIGMA 10514 in PT PAL Shipyard Indonesia, a second contract was signed in February 2013.
 * Morocco has ordered two 9813 class heavy corvettes (with VLS) and a light 10513 class frigate based on a modified design.

Potential Users

 * Vietnam has negotiated four SIGMA in October 2011 by Prime Minister Nguyen Tan Dung's visiting to Netherlands. The Dutch Schelde shipyard in Vlissingen, Netherlands will build four Sigma corvettes for the Vietnamese Navy. The first two ships will be built in Vlissingen, and the last two will be built in Vietnam, under Dutch supervision.
 * Oman had an interest in buying four SIGMA corvettes/frigates in March 2011. The Dutch queen Beatrix planned a state visit to Oman, one of the reasons for the visit was the sale of the ships to the Royal Navy of Oman.The official visit was cancelled due to the unrest in Oman at the time, she did go to an unofficial dinner with the sultan of Oman. The official visit took place later in January 2012. During the first visit to Oman the Royal Netherlands Navy sent its air defence warfare frigate HNLMS De Ruyter (F804) to Muscat.
 * Philippines The Damen Schelde shipyard reportedly join and might offered Sigma class Light Frigate version for the bidding of Philippine Navy 2 brandnew frigate requirements, but no other information added.

Indonesian variants
SIGMA 9113

The Indonesian variant is based on the Sigma 9113 design. Work on the first of the class, KRI Diponegoro, began with the first steel cutting conducted in October 2004. The ship was christened on September 16, 2006 and commissioned on July 2, 2007 by Admiral Slamet Soebijanto, Indonesian Navy Chief of Staff.

Options for 2 other units were exercised on January 2006 with the first steel cut commenced on 3 April 2006 in Damen's Schelde Naval Shipbuilding yard, Vlissingen-Oost yard and not in Surabaya stated earlier.

In 28 August 2007, Jane's Missiles and Rockets reported that Indonesia was having problems securing the export license for the MM-40 Exocet block II and are considering Chinese made C-802 anti-ship missiles as alternatives. However, the ships have already been delivered with the Exocet missiles.

SIGMA 10514

On the 16 August 2010, Indonesia Defense Department, signed a deal with PT PAL Indonesia and Damen Schelde to build a 105 meters frigate in Indonesia based on Damen Schelde Sigma 10514 design. The frigate will be equipped with 76mm Main Canon, 12 MICA vertical launch air defence missile, MM-40 Exocet block II, Torpedo, phalanx and SMART-S MK2 radar system. Though the Indonesian Navy announced that it will build four destroyer escorts referring to the SIGMA 10514. On the Indo Defence 2012 exposition a model was revealed showing the phalanx and ASW mortar replaced by a single 35 mm Oerlikon Millennium Gun system, also the 76mm had a stealth cupola. Some reported that the VLS missiles will be Aster-15 instead of MICA, due to these changes the ships role also changed from ASW to AAW.

On February 1, 2013 it was announced that a second unit will be build by Damen Schelde Naval Shipbuilding and PT PAL Surabaya, the second contract includes torpedo tubes, combat control room and a couple of surface weapons.25

Moroccan variants
On February 6, 2008, Morocco signed a USD$1.2 billion contract with Schelde Naval Shipbuilding for two Light frigate SIGMA 9813 and one Light frigate SIGMA 10145 which are modified versions of the existing SIGMA Class design.

A subsequent contract was signed on the April 1, 2008 with Thales Nederland for the supply and installation of the command and control and sensor package for the ships. The package included TACTICOS combat management system, SMART-S Mk2 surveillance radar, LIROD Mk2 tracking radar, Thales KINGKLIP sonar system, IFF system, Integrated communication system comprising external communication system and FOCON internal communication system, two Target Designation Sights, VIGILE ESM system, SCORPION ECM system, and the integrated navigation system.

The first frigate for Morocco, Tarik ben Ziyad, was launched in July 2010, began sea trials on 6 May 2011 and was delivered on 12 September 2011. The second ship was launched on 2 February 2011, with sea trials planned for late in the year. The third ship was planned to be launched in September 2011.

Ships of class
TNI-AL / Sigma 9113 design

TNI-AL / Sigma 10514 design

Moroccan Navy / Sigma 9813 & 10513 design

Note: 613 now shows on AIS as Sultan Moulay Ismail.

Sigma versions
Simplified comparisons between the different Sigma models.