The Invincible’s improved ocean-going capabilities means it could also contribute to longer range patrols of sea lines of communication in the Indian Ocean, or to Taiwan, with which it has a defense partnership.

On February 18, 2018, officials gathered to celebrate the launch of a new state-of-the-art submarine at a shipyard in Kiel, Germany. But unlike similar Type 212 submarines previously built there, the seventy-meter long diesel-submarine isn’t destined to shadow Russian submarines in the cold waters of the Baltic Sea.

(This first appeared earlier in the month.)

Instead, the Invincible will lurk in the warmer Pacific waters around the Straits of Malacca in the service of the Republic of Singapore Navy. In so doing, the 2,000-ton submarine and her three forthcoming stablemates will become new factors in the ongoing multi-national competition for influence over the South China Sea.

Singapore is an island city-state sitting astride the Straits of Malacca, which offers the most direct route for commercial traffic between East Asia and the Indian Ocean—totaling one-fourth of all the world’s traded goods, including a quarter of all oil.

The wealthy but tiny nation has invested in an unusually capable and expensive military for its size—in 2017 it had the fifth highest defense spending per-capita on the planet. It has purchased major Western weapon systems including 100 F-16 and F-15SG fourth-generation jet fighters, Leopard 2 tanks and most recently, four to twelve F-35 stealth fighters.

Singapore is adjacent to two more populous countries (Malaysia and Indonesia) and also holds China as an important commercial partner. However, it has insisted China’s claims to sovereignty over large swathes of the South China Sea should be adjudicated by legal means, and hosts U.S. Navy P-8 maritime patrol planes and Littoral Combat Ships.

Thus, while Singapore considers itself a neutral actor, it is sometimes perceived as tilting more towards Washington to counterbalance China’s growing military power. Not incidentally, Beijing has explored bypassing Singapore through construction of the Kra canal through Thailand.

The Invincible, also designated the Type 218SG, joins the growing numbers of air-independent propulsion (AIP) submarines active in the Pacific Ocean in the navies of China, Japan, Singapore and South Korea. AIP allows a comparatively cheap diesel-electric submarine to cruise underwater at slow speeds for weeks at a time, instead of having to surface or snorkel every few days.

The Type 218, as with contemporary German designs like the Type 212 and 214, uses hydrogen fuel-cells for this purpose, a more advanced and less noisy configuration than the Stirling heat-cycle AIP engine used on Singapore’s two Swedish-built Archer-class submarines which entered service in 2011 and 2013. The Invincible is said to have 50 percent greater endurance than the Archers, implying it can remain submerged four to six weeks before needing to surface. Fuel-cell AIP does have the disadvantage of being more expensive and is potentially volatile should the submarine sustain damage, however.

AIP submarines still can’t sustain speeds of 30 knots and remain underwater indefinitely the way a nuclear submarine can. The Type 218 reportedly has top underwater speed of 15 knots, or 10 knots surfaced. But AIP-submarines cost one-fourth or less the price of a nuclear sub, and their limitations are not nearly as important when engaged on shorter-range patrols.

Germany has already exported chubby Type 214 export submarines to South Korea in Asia. However, Singapore sought a slightly larger, more advanced design to replace its old Challenger-class submarines, which Singapore first purchased from Sweden in the 1990s.

The Type 218 boasts a sophisticated new combat system jointly developed by Germany and Singapore featuring computer-assisted decision-making algorithms. The resulting high degree of automation allows a crew of only twenty-eight to operate the sub, rotating on eight-hour shifts instead of more fatiguing twelve-hours. This could leave more room for intelligence-gathering specialists or special operations troops.

The Type 218SG can also carry a heavier weapons load, with eight tubes for launching 533-millimeter heavyweight torpedoes instead of the more typical six. While official details of onboard armament remain unavailable, in addition to heavyweight torpedoes, the Type 218 tubes could conceivably be outfitted with naval mines or anti-ship or land-attack missiles like the Harpoon and Tomahawk, or the German fiber-optically guided IDAS missile, which can hit both surface targets and slower-moving aircraft like sub-hunting helicopters.

In a statement to media, Singaporean defense minister Ng Eng Hen emphasized the submarine’s usefulness for various peacetime operations, including curbing piracy, arms smuggling and human-trafficking. However, the Type 218s also give the island state an intimidating conventional deterrence capability: if Singapore feels threatened or compelled to join an international alliance in a crisis, its submarines could effectively deny access to the ultra-valuable strait. Even a numerically superior adversary would struggle to hunt down long-endurance submarines that can remain submerged for over a month at a time.

The Invincible’s X-shaped rudder also affords it greater maneuverability—useful for navigating the shallow, rocky Strait, which is only 1.5-miles wide at its narrowest point. The strait has many small inlets and islands, around which a submarine could settle onto the sea floor and wait in ambush, while remaining extremely difficult to detect.

The Invincible’s improved ocean-going capabilities means it could also contribute to longer range patrols of sea lines of communication in the Indian Ocean, or to Taiwan, with which it has a defense partnership.

More routinely, the Type 218’s advanced sensors and facilities will give Singapore significant intelligence-gathering capabilities, particularly for intercepting signals, deploying operatives, tracking the movements of Chinese diesel-electric submarines around the strait and building a “threat library” on their acoustic signatures. Such intelligence may be exchanged with United States and regional partners, with which Singapore has shared intelligence in the past.

The Type 218’s potential uses and areas of operation are explored in greater detail in this article by Peter Coates in Submarine Matters.

For now the Invincible is set to begin sea trials while a crew commanded by Lt. Col. Jonathan Lim is training in Germany, preparing for commissioning in 2021. Meanwhile, her sister ships Impeccable, Illustrious and Indomitable are set to be launched in 2022, 2024 and beyond, respectively, with the latter eventually replacing Singapore’s Archer-class submarines.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.