6 things to note about the RSN Invincible-class submarines, Impeccable and Illustrious

On Tuesday (13 December 2022), Singapore Prime Minister (PM) Lee Hsien Loong officiated at the launch ceremony for the Republic of Singapore Navy (RSN)'s second and third Type 218SG Invincible-class submarines, Impeccable and Illustrious, at thyssenkrupp Marine Systems (tkMS) shipyard in Kiel, Germany.

The ceremony marked a rare occasion when observers could take a close look at the 70-metre long, 2,000-ton boats, which look set to be the largest and most advanced diesel-electric, AIP-capable hunter-killer submarines in Southeast Asia.

The Type 218SGs, the largest submarines designed and built by the German yard, had been photographed on many occasions while on sea trials. But the images and videos were all taken from a distance. 

The launch ceremony for the name ship of the class, Invincible, in February 2019, had the boat hoisted out of the water, with her upper hull and deck features not visible to guests.

While the sight of two submarines side by side was visually appealing, there's a lot left unsaid about what these boats can do. 

Here are six things that caught our attention (kementah.blogspot.com):

Number 1: Hull features

The decorative, wrap-around bunting that was painstakingly tied by hand made one think about why so much effort went into dressing the boat. Naval observers would prefer a clean, naked hull with all protuberances visible. It was interesting to note that the level at which the bunting was secured could correspond to the parts of the boat's hull where one would normally find tubes for torpedo countermeasures.

Number 2: Screw
Just as Type 219SG's hull was on show - yet not shown fully thanks to the bunting - neither was the boat's screw. The blade count and shape of blades are normally points of interest for ship watchers. At Tuesday's ceremony, the screws for both boats were not visible as the water level in the dock kept their design features out of sight.

Number 3: Combat management system

Seventy metres of steel shark is a lot to behold. What you do not see is the heart of the fighting machine - the combat management system (CMS) that makes the boat a man-of-war. If Singapore's Defence Science & Technology Agency (DSTA), the national authority on weapon systems, takes a leaf from the Formidable-class stealth frigate project, then the software for the CMS is likely to be bespoke. 

This milestone is significant. The Formidable-class CMS benefitted from years of experience developing and fielding similar systems for the Republic of Singapore Air Force (RSAF). The frigate's abovewater sensor suite, which tracks surface and aerial contacts, is essentially a mobile and seaborne version of radars and other sensors used by the RSAF.

A submarine's CMS suite, however, demands rather different skillsets. It is more challenging than applying the know-how needed to display and interprete data from a ground-based radar to a shipborne radar. 

The expertise needed to master underwater sensors is in a class of its own. These include sensors like active and passive sonar technology. Operating conditions beneath the waves are also different and engineers must develop an appreciation of water conditions - temperature, salinity, prevailing currents and tidal flows - and things like the seabed profile and acoustic conditions in the area of operations for the CMS to make sense of what is around the submarine. Otherwise, the sub fights blind.

So watch closely for any signs of the degree of local involvement in the submarine CMS, as this would telegraph a noteworthy step up in Singapore's defence engineering expertise.

Number 4: Mast

In some navies, every mast and device on the conning tower is raised to demonstrate the sub's mast-mounted sensor suite. One guesses that the time isn't quite right for the Invicible-class. But take note of the mast configuration when they do.

Number 5: Number of bunks

It was interesting to read that all 28 crew members on the Type 218SG would have their own bunks. On subs, the bunks are usually shared by crew members on different watches - a practice known as hot bunking - in order to save space aboard the sub. If you read between the lines, this could mean that the Type 218SG could, theoretically, embark up to 14 personnel who are not part of the boat's crew. This assumes the boat practices hot bunking, with the empty sleeping spaces allowing more warm bodies aboard. Food would be an operational limitation, but with dry rations and ample space on the boat, will not be a weighty hinderance to ops planning. Rather interesting fictional scenarios one could write about with half a platoon of special forces types onboard for insertion by sub.

Number 6: Operational tempo

Four boats on call suggest that the RSN could maintain a high operational tempo with the Invincible-class boats, once all are commissioned into active service around the end of the decade. Four boats means you could have one for training, one undergoing maintenance or refit, with a balance of two for operational taskings.

In summary, interesting times ahead for the RSN's unerwater warfare community.

If you like submarines, do note that my new book, Pukul Habis - Total Wipeout, has several chapters on the exploits of the Royal Malaysian Navy submarine, KD Tunku Abdul Rahman, as the boat embarks on her first war patrol with Exocets, Black Shark torpedoes and the boat's SUBTICS combat management system.

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