The Type 218SG or Invincible-class submarines are being built by ThyssenKrupp Marine Systems for Singapore Navy. Credit: The Government of Singapore.
The submerged speed of the Invincible-class submarine will be more than 15k. Credit: The Government of Singapore.
The first Type 218SG submarine was launched in February 2019. Credit: thyssenkrupp AG.

Four Invincible-class submarines are being built by German shipbuilder ThyssenKrupp Marine Systems (TKMS) for the Republic of Singapore Navy (RSN).

The submarines, also known as Type 218SG, will replace the RSN’s current Archer-class, and Challenger-class submarines that were built in the 1960s.

Named Invincible, Impeccable, Illustrious, and Inimitable, the four diesel-electric submarines will be a part of the RSN’s submarine long-term capability development and force renewal programme and will also meet its operational requirements.

Invincible-class submarines development

Singapore’s Ministry of Defence (MINDEF) signed a contract with TKMS for the acquisition of the first two Type 218SG submarines in December 2013.

In May 2017, the MINDEF signed a new contract with the company for two additional Type 218SG submarines. The contract also includes delivery of logistics package and a crew training arrangement in Germany.

The steel cutting ceremony of the first two submarines was held at the TKMS shipyard in Kiel in 2014. The first two vessels are scheduled for delivery in 2022 while the remaining two will be delivered from 2024.

"Named Invincible, Impeccable, Illustrious, and Inimitable, the four diesel-electric submarines will be a part of the RSN’s submarine long-term capability development and force renewal programme."

The first Type 218SG submarine in class, Invincible, was launched in February 2019. The factory sea trails of Invincible started in Kiel, Germany, in September 2020.

Singapore’s Defence Science and Technology Agency (DSTA) and TKMS signed a memorandum of understanding (MOU) for the development of new technologies, including additive manufacturing and data analytics for producing submarine spare parts. Atlas Elektronik and ST Electronics are responsible for developing the combat system.

RSN is also developing a submarine trainer suite (STS), which will meet the training requirements of the Type 218SG submarines. The suite will include a command team trainer, steering and diving trainer, virtual procedural trainer, and maintenance trainer.

Invincible-class submarine design and features

The Type 218SG vessels retain the design features of Type 214 and Type 212A submarines such as the X rudder layout that will enable the vessel to manoeuvre in shallow littoral waters.

The submarine will have an overall length of 70m and a diameter of 6.3m and will have the capacity to accommodate 28 crew members. The displacement of the vessel will be 2,000t when surfaced and 2,200 when submerged.

The crew members will be provided with their own bunk, larger living space, and additional showering and toilet cubicles.

The submarines will feature innovation and advanced maintenance and engineering concepts to enhance training, operation, and maintenance.

Armament and sensors

The submarines will be armed with modern combat systems, including eight torpedo tubes of 533mm. The bow section of the vessel will integrate a horizontal multi-purpose lock (HMPL) for launching torpedoes, missiles, and special forces assault teams, and an option to integrate vertical multi-purpose locks (VMPLs) for launching missiles vertically.

Advanced sensors on board the submarine will improve situational awareness in both shallow and congested waters. The next-generation automation and sense-making systems will further help in fast decision making.

The advanced automation systems will enable it to run on three four-hour shifts, enabling the crew to take more rest for extended endurance.

DSTA developed advanced systems such as data analytics and decision support engines, which will enable the submarines to act faster.

Propulsion and performance of Invincible-class

The Invincible-class submarine will be powered by the air-independent propulsion system. The vessel will have a surface speed of more than 10k and a submerged speed of more than 15k.

The submarines will have the capability of staying submerged for approximately 50% longer compared to the Archer-class submarines as it is fitted with an advanced air-independent propulsion system based fuel cell technology.

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