August 11, 2014

Toward Stealth and Sea Denial: Submarine Modernization in East Asia

What technology might Singapore's 218SGs incorporate: fuel cell or Stirling AIP, Vertical Multi-Purpose Lock (VMPL) or Lithium-ion batteries? (Diagram courtesy of Globalsecurity)

The following is another excellent article* by Michael Raska, Research Fellow, Institute of Defence and Strategic Studies, S. Rajaratnam School of International Studies (RSIS), Nanyang Technological University, Singapore. The article details competition involving ever larger, more numerous and more capable submarines in Northeast and Southeast Asia. 

I maintain that Australia will need to respond to this strategic submarine competition be acquiring a new class of larger SSKs or more prudently SSNs. This is in recognition that only SSNs can perform all the roles required of a modern submarine force. 

Michael Raska's article was published by RSIS on July 7, 2014 in html at and also in pdf at

Toward Stealth and Sea Denial: Submarine Modernization in East Asia

IDSS / RSIS / Commentaries / East Asia and Asia Pacific / International Politics and Security / Maritime Security
07 JULY, 2014

RSIS Commentary No. 130/2014


An important aspect of the regional “arms competition” in East Asia is the gradual introduction of new classes of conventionally-powered diesel-electric submarines (SSKs), which are increasingly becoming “platforms of choice” – as force-multipliers in diverse missions as well as against superior forces.


Notwithstanding East Asia’s economic growth rates and deepening integration into the global economy, the region’s strategic realities reflect contending trajectories. As China expands its national interests in the broader context of “new historic missions”, it seeks to regain a great power status and reassert its geopolitical role in the region. As a result of China’s accelerating military modernization, regional powers are responding by revamping their force modernization priorities, alliances, and overall strategic choices.

The economic, political, and military rise of China, embedded in three decades of relentless Chinese economic growth, has propelled progressive modernization of the Chinese military with major improvements in virtually every capability domain.

China’s Naval Modernization and Submarine Expansion

Notwithstanding weaknesses and limitations in capabilities integration, China’s PLA Navy (PLAN) is gradually transforming toward a regional [blue water] defensive and offensive type navy with extended so-called anti-access/area-denial (A2/AD) capabilities, limited expeditionary capabilities, and corresponding defensive and offensive air power. China calls its comprehensive A2/AD strategy a “counter-intervention”, which is interpreted as denying the U.S. and its allies the freedom of action in China’s ‘near seas’ by restricting their deployments into theatre (anti access) and denying them freedom of movement there (area denial).

An important aspect of China’s multilayered strategy is the gradual introduction of new classes of submarines – both nuclear and conventional. China is currently operating as many as 45 submarines structured in six different classes: two classes of indigenously designed diesel submarines, including the Song class (Type 039) and the Yuan-class (Type 041), and four nuclear classes that include the Shang-class (Type 093), Jin-class (Type 094) nuclear powered ballistic missile submarines (SSBN) and the follow-on Type 095 nuclear-powered attack submarine (SSN) and Tang-class (Type 096) SSBN.
Since 2004, China is believed to have launched 12 Type 041 Yuan-class conventional submarines, which have been progressively modified to carry more advanced high-frequency sonar, upgraded weapons systems, noise reduction and air independent propulsion (AIP) technologies. The PLA Navy may procure up to 20 additional Yuan-class submarines based on technologies imported from Russian boats. Since the mid-1990s, China has procured as many as 12 Kilo-class submarines from Russia, and is reportedly negotiating the purchase of at least four fourth-generation Amur (Lada)-class or possibly a fifth-generation Kalina-class, both featuring advanced AIP systems.

Regional Responses

In Northeast Asia, Japan and South Korea are prioritizing the procurement of new types of submarines. In September 2013, South Korea launched a fourth 1,800 ton Son Won-ill class (German Type 214) submarine, featuring AIP and combat management systems. South Korea now operates 13 submarines: nine Type 209 Chang Bogo and four Son Won-ill class submarines. Meanwhile, in October 2013, the Japan Marine Self Defense Force (MSDF) launched its newest submarine the Kokuryu – the sixth of planned ten Soryu class boats first commissioned in 2009. With its range, endurance, sensors, weapons load and other systems, including the Stirling AIP propulsion system and Harpoon anti-ship missiles, the Soryu class is regarded as the most advanced in Japan’s conventional submarine fleet of 16 submarines.

In Southeast Asia, the relatively high acquisition costs and maintenance requirements have traditionally precluded a quantitative diffusion of submarines. However, the recent introduction of more capable coastal diesel-powered submarines provides unprecedented capabilities. Most recently, Vietnam received two of six Kilo-class (Project 636) diesel-electric submarines from Russia in 2013- 2014, designed for diverse reconnaissance and patrol, anti-submarine and anti-ship missions.

Indonesia, Malaysia, and Singapore are also planning to expand or upgrade their submarine fleets. From 2007-09, Malaysia took formal delivery of two French-built Scorpene-class submarines, equipped with underwater-launched Exocet anti-ship missiles. Both submarines are based at the Kota Kinabalu Naval Base in Sabah, East Malaysia, indicating their primary mission to protect Malaysia’s sovereignty in part of South China Sea. Meanwhile, Indonesia has ambitious plans to expand its submarine fleet to at least six, and ideally to 12 by 2024, a key element in the “Minimum Essential Force” (MEF) and declared goal of developing a ‘green-water’ navy. In 2012, the Indonesian Navy (TNI-AL) announced a US$1.1 billion contract for three Type-209/1400 diesel-electric submarines, constructed by South Korea’s Daewoo Shipbuilding and Marine Engineering.

In November 2013, Singapore announced a contract with German shipbuilder ThyssenKrupp to acquire two advanced Type-218SG submarines that will augment existing Archer-class boats and replace ageing ex-Swedish Challenger-class by 2020. Type-218SG, designed for littoral, shallow sea operations, is a customized design that will integrate features from Type 214 and possibly Type-216 ‘concept submarine’ fitted with fuel-cell AIP system. [Pete's Comment - the atypical 218 designation might also suggest that the 218s might be fitted with Stirling engine AIP in line with the Stirlings already incorporated into Singapore's two Archer class subs.]

Strategic Ramifications

Over the past decade, the operational utility of submarines in East Asia has widened: from anti-submarine warfare to force protection such as close submarine escort missions, intelligence surveillance, and reconnaissance (ISR), support of Special Forces, and other complementary deterrence and defensive tasks supporting territorial defense. At the same time, the introduction of submarine-launched anti-ship and land-attack cruise missiles, anti-submarine sensors and weapons, as well as air independent propulsion systems have increased their stealth capacity to remain undetected shortened their target-identification-and-attack cycle, and ultimately, improved their flexibility, mobility, endurance, reach, and lethality.

For smaller, defensively-oriented navies in East and Southeast Asia, these attributes enable “sea-denial” capabilities aimed at preventing an opponent from using the sea, rather than providing a degree of sea control to use the sea for own power projection. Submarines will therefore become an increasingly valuable strategic asset in the region, particularly with installed AIP systems. The key difference, however, will be in the experience, training, and skill set of its operators."

Michael Raska's earlier submarine article appeared on this blog on July 31, 2014 as Air Independent Propulsion - A Game Changer .


Anonymous said...

Dear Pete,

I don't expect the 218 to have a sterling engine. I just can't see a reason for TKMS to use the Stirling engine for obvious reasons... The core of the Stirling engine on Kockums submarines is owned by Sweden.

According to wikipedia one Stirling engine drives an 75 kW generator. So the power output for Japanese Sōryū-class submarines is 300 kW.

The latest batch of German Type 212 has 2 fuel cells at 120 kW each. Add a third cell and you reach 360 kW.

According to the "70 % efficiency" of fuel cells. I guess this is the amount of energy transfered into electrical useful energy compared to the sole heat energy.

I read somewhere a nice story why the submarines for Singapore a relabeled to 218. "214" sounds like "sure to die" while "218" sounds like "sure to prosper".
"8" is also a lucky number in Asia.


Pete said...

Hi Matthias

Your data on the kW output comparison of fuel cell and Stirling engines is very useful - with 70% efficiency being a good reason to choose fuel cell. I have a suspicion though that when TKMS owned Kockums the Singaporean Government ordered Stirling engines for the 218s.

It would still be in Sweden's interests to supply Stirlings to the TKMS for the 218s. That way Sweden at least gets some money from the 218 deal.

Its probably true that the 218 designation is for the Cantonese phonetic reasons that you state.

However, with the passage of time there have been some major technical advances in submarines that justify a numerical designation up from 214.

I'm fascinated with what improvements that would be incorporated in the 218. The Singaporean Government and TKMS-HDW would know what they are. I expect they have officially provided such information to the Australian Government.

However I remain separate from the Australian government so remain ignorant.



Anonymous said...

Dear Pete,

I still believe Type 218 won't have a Stirling engine. For the refurbished Archer-class the Sterling engine was the indigenous and cheap solution.

Other nations do not have problems to switch to another system in case this system is better (SEA 1000 command and control system).

The fuel cells offer more range for the same amount of fuel.

There is another advantage for fuel cells I missed to mention: partial load.
Any heat driven engine has a optimal running speed and work load. Superfluous energy has to be stored or wasted.
The current a fuel cell delivers can be tuned by the amount of gas you provide to it.

A submarine on low power would need to run a Stirling engines for some time and then switch back to battery. Storing energy will always lower efficiency. A fuel cell will deliver the exact amount of power for the whole period without the use of batteries.


Anonymous said...

Dear Mr. Raska,

I stumbled about a sentence within your commentary:
"Type - 218SG, designed for littoral, shallow sea operations [...]"

Type 212 have a guaranteed diving depth of 400 m and a designed depth of 700 m. Compare that to the "allowed" diving depth of Collins-class...

A under water explosion is nothing else than pressure wave. A submarine with weak valves will be damaged by explosions much further away compared to a submarine with a better diving depth.

According to unofficial range estimations the Type 214 is close to Collins-class.


Pete said...

Hi MHalblaub

I hazard to guess that the 218s will have the same guaranteed diving depth of 400 m - designed depth of 700 m as the 214s.

Talk of depths prompted me to study Singapore's subs likely operating environment

Possibly Singpore's submarines highest priority operating area is "In the south of the Malacca strait, [where] water depths rarely exceed 120 feet (37 metres) [making night-time operation advisable] and are usually about 90 feet (27 metres). Toward the northwest, the bottom gradually deepens until it reaches to about 650 feet (200 metres) as the strait merges with the Andaman Basin."

Geologically, the Malacca strait belongs to the Sunda Shelf. This Shelf is a platform "covered by shallow seas—including the southern South China Sea, the Gulf of Thailand, and the Java Sea—with depths averaging less than 330 feet (100 metres).

Hence the 218s (are/will be) designed for shallow sea ops.

Also interesting that German subs in WWII operated in nearby Penang (Malaysia). One U-Boot U-862 travelled all the way around Australia and on to New Zealand