Invincible-Class Might Not Be Nuclear But She Packs a Big Submarine Punch
Merriam-Webster’s Dictionary defines the word “invincible” as “incapable of being conquered, overcome, or subdued,” and uses “a seemingly invincible army” as an example.
It is no surprise that the word “invincible” has also been repeatedly used as a warship name. Great Britain’s Royal Navy has given the name to seven ships. One of them, launched in 1907, was the world’s first battle cruiser.
She didn’t quite live up to the lofty moniker, as she was sunk during the epic Battle of Jutland in May 1916.
The light aircraft carrier HMS Invincible, launched in 1977, fared better, serving in the Falklands War, the Yugoslav Wars, and the Iraq War before being scrapped in 2011.
Now, the “Invincible” moniker is attached to the submarines of the navy of a former British colony in Southeast Asia.
Say hello to Singapore’s Invincible-class diesel-electric submarines.
Invincible-Class (Type 218SG) Initial History
Designated as the successors to Singapore’s Archer-class boats, Singapore’s Invincible-class subs are built by ThyssenKrupp Marine Systems, headquartered in Kiel, Germany.
Two are currently in active service.
Both were ordered in 2013 and commissioned on September 24, 2024.
The lead ship of the class is the RSS Invincible, launched on February 18, 2019, followed by the RSS Impeccable, launched on December 13, 2022.
Two others, the RSS Illustrious and Inimitable, were ordered in 2017 and launched on December 13, 2022, and April 22, 2024, respectively. They are currently undergoing sea trials.
According to the World Directory of Modern Military Warships, the current submarine fleet of the Republic of Singapore Navy also includes two of the aforementioned Archer-class subs and two hulls of the Challenger-class—though other reports indicate the Challengers were decommissioned in late 2024.
Invincible Tech Specs and Vital Stats
Courtesy of Seaforces-online:
Displacement: 2000 tons (surfaced) / 2200 tons (submerged)
Length: 70 meters
Beam: 6.3 meters
Draft:?
Speed: 10 knots surfaced/20 knots submerged
Range:?
Endurance: 28-42 days underwater
Complement: 28 commissioned officers and enlisted seamen
Propulsion:
2 x Diesel generators
2 x PEM fuel cells (air-independent propulsion)
1 x electric motor
1 shaft, 1 propeller
Armament:
8 x 21-inches (533 mm) torpedo tubes for heavyweight torpedoes, submarine-launched anti-ship missiles, and naval mines.
The Invincibles run on air-independent propulsion (AIP), which considerably boosts the endurance of a diesel-electric boat (though it is still considerably less than a nuclear-powered submarine).
One of the more unique features of the Invincible-class is its X-shaped rudder configuration, similar to that of the Israeli Navy’s Dakar-class submarine.
It allows for better maneuverability in Singapore’s busy but shallow littoral waters around the Straits of Malacca and the South China Sea.
It is better in these waters than the Type 214‘s cruciform rudder configuration.
Operational History and The Way Forward
There is limited operational history to report. Singapore hasn’t been directly involved in a war since World War II, when it was captured by Imperial Japan and occupied until 1945.
As for the way forward, Singapore’s Ministry of Defense reported the following on May 8, 2025:
“The Ministry of Defence has signed a contract with thyssenkrupp Marine Systems GmbH to acquire two additional Invincible-class submarines. The procurement of two additional submarines was previously announced by the Minister for Defence at the Committee of Supply 2025. … The additional submarines are projected for delivery from 2034 as part of the RSN’s submarine force renewal programme to meet operational requirements. Two of the four existing Invincible-class submarines, RSS Invincible and RSS Impeccable, have been commissioned in Sep 2024. The trials and acceptance for the third and fourth submarines, Illustrious and Inimitable, are progressing well in Germany, and they are expected to return to Singapore by 2028.”
About the Author: Christian D. Orr
Christian D. Orr is a Senior Defense Editor. He is a former Air Force Security Forces officer, Federal law enforcement officer, and private military contractor (with assignments worked in Iraq, the United Arab Emirates, Kosovo, Japan, Germany, and the Pentagon). Chris holds a B.A. in International Relations from the University of Southern California (USC) and an M.A. in Intelligence Studies (with a concentration in Terrorism Studies) from American Military University (AMU). He is also the author of the newly published book “Five Decades of a Fabulous Firearm: Celebrating the 50th Anniversary of the Beretta 92 Pistol Series.”
