SINGAPORE – Often referred to as the silent service for their ability to go unnoticed while tracking down enemy ships, submarines have played a decisive role in major conflicts for more than a century, since the Germans used submarines with devastating effect during World War I.

But the recent sinking of the Indonesian submarine KRI Nanggala 402 has highlighted the dangers associated with the operation of these complex war machines, designed to be “ship killers” that operate for long periods of time in a ruthless underwater environment. .

The loss of 53 crew members aboard the Nanggala in April after losing contact during a training exercise was the fourth recorded accident since 2000 in which an entire submarine crew perished.

In 2017, Argentina’s submarine ARA San Juan and its crew of 44 disappeared off the coast of the country during a training exercise. Her wreck was found a year later.

In 2003, a Chinese submarine was at sea off northeastern China when the diesel engine did not stop as the boat submerged and all oxygen was depleted, killing all 70 people on board. .

The Russian nuclear submarine Kursk sank in the Barents Sea in 2000 after an explosion, with no survivors among its 118 crew members.

The many risks to submariners include those posed by the literal high pressure underwater environment, which provides extremely slim margins of error. An incident such as a fire on board or a power failure can quickly escalate and become catastrophic.

So why do Singapore and other Southeast Asian countries continue to acquire and operate these assets, even smaller regional navies finding the risks worth their investment?

The answer lies in the strategic nature and versatility of these deep-diving predators, which have been proven successful in naval history.

While the earliest prototypes of submarines date back to the 16th century, they first established themselves as a military weapon during World War I, when they primarily played the role of trade looters.

Then German submarines – short for Unterseeboot – sank around 5,000 ships, mostly merchants and civilians, carrying crucial supplies to the British.

During World War II, submarines became more versatile and deadly, adding visual surveillance of enemy coasts and the insertion of secret agents or special operations forces to their repertoire, Mr. Ben said. Ho, researcher at the S. Rajaratnam School of International Studies (RSIS).

American submariners, for example, never made up more than 2% of the total force of the United States Navy during World War II, but the ships they operated made up more than 55% of all Japanese ships sunk in the Pacific, according to Mr. Don Keith, who wrote the book Final Patrol: True Stories Of World War II Submarines.

At present, Mr Ho said, the typical attack submarine is like a Swiss army knife with various missions, as opposed to its rarer cousin to ballistic missiles whose raison d’être is nuclear deterrence. .

“The submarine is a very versatile platform which – thanks to its stealth and ability to create surprises – offers an asymmetrical advantage to its operator, even weak against a strong opponent à la David vs. Goliath.”

Citing an example of the strategic impact of submarines, Collin Koh, a researcher at RSIS, said that the sinking of the Argentine cruiser ARA General Belgrano by the British HMS Conqueror during the Falklands conflict of 1982 between the two countries had a profound impact on Bueno Aires.

“The Argentine Navy’s surface fleet, including its only aircraft carrier ARA Vienticinco de Mayo, was confined to port and did not carry out any sortie (deployment) during the remainder of the conflict,” he said. declared.

As for Singapore, it entered the depths with the commissioning of the RSS Conqueror in July 2000. The Republic of Singapore Navy currently operates four refurbished Challenger and Archer class submarines.

They will be replaced by four advanced type 218SG submarines custom-built by German defense contractor thyssenkrupp Marine Systems, the first of which is expected to be delivered from next year.

Regional countries such as China, India and South Korea also have plans to expand their submarine fleets.

Closer to home, Vietnam operates the largest fleet in Southeast Asia with six submarines. Indonesia had five before the recent sinking. Malaysia operates two and Thailand has one on order.

The Philippine Navy has repeatedly advocated for the constitution of a submarine force. Myanmar received a Soviet-era submarine from the Indian Navy last year.

Dr Koh believes even a small “token” fleet is important because it could act as a deterrent, although he warned that even a small force could be costly to acquire, operate and maintain.

He cited the United States’ confrontation with Muammar Gadhafi’s Libyan regime in the 1980s, where the US Navy was concerned about the latter’s tiny fleet of Soviet-built submarines, despite their poor readiness.

Australia was also concerned about the potential challenge posed by the two Indonesian Cakra-class submarines, including the ill-fated Nanggala, when leading a multinational peacekeeping force in East Timor in 1999, added Dr Koh.

“Even a small submarine force would be a worthwhile investment in the eyes of Southeast Asian navies, which are generally small and weak compared to their more powerful regional counterparts,” he added.

In other words, a submarine is like a mobile minefield that injects uncertainty into an enemy’s planning because it poses an elusive but deadly threat, said the secretary of the Submarine Institute of Australia, Frank Owen, who served in the Royal Australian Navy for 31 years.

Dr Koh added: “Classical threat perceptions are not necessarily the key or the only driver of the Southeast Asia submarine quest; it’s also about catching up with the Joneses, as we see in the case of Thailand, for example. .

“It’s not so much that neighboring submarines pose a real threat, but that if you don’t buy submarines as well, you risk falling behind in the construction effort. ‘a modern and balanced fleet. “

As they strike over their tonnage, submarines face a variety of operational risks, although they are typically piloted by some of the most elite military professionals selected through a rigorous process. The biggest risk is collisions, Owen said.

A submarine can almost never be seen by a surface ship, he said. Even when it does surface, the silhouette of a submarine is small.

When underwater, it hears noises made by other ships, but the sound may be distorted so that a submarine may not hear anything when it returns from the depths until it is too late, he added.

In 2001, the US submarine USS Greeneville collided with a Japanese fishing vessel while surfacing after a dive, sinking the vessel and killing nine of the 35 people on board, including four high school students.

Like a warship, a submarine has instruments and sensors to ensure its safety even in difficult conditions. But unlike a vessel on the surface which will stay afloat as long as the hull is intact, she is inherently less safe.

On a submarine, small mistakes can have dire consequences because emergencies do not happen in isolation, said Anil Jai Singh, senior vice president of thyssenkrupp Marine Systems.

“One thing leads to another, which could turn catastrophic if not treated properly and on time. Sometimes even the best response may not save the situation which evolves very quickly,” he said.

This means that even a small problem can quickly escalate and cause the crew to lose control of the submarine, or cause the boat to lose neutral buoyancy and sink, said Bryan Clarke of the Washington-based Hudson Institute.

Mr Singh said the two most important emergencies are either a major flooding due to a broken pipeline or damage to the hull, or a major fire on board that could lead to a blackout, explosion. internal, smoke and suffocation or rising water levels inside the submarine.

While there are redundancies built into critical systems, these can fail, he added.

The high-pressure environment means that a breach in the hull can produce a jet of water that is several times the force a surface vessel could experience, Owen said.

“Any deep flooding quickly gets out of control and the weight of the water carried in the submarine can quickly exceed the buoyancy that could be provided by emptying the ballast tanks.”

Mr Singh, a 28-year former Indian Navy submariner, speculated that in the case of the Nanggala, assuming it was diving at a cautious speed of 5 knots with a descending angle and loss of power, it would have took less than three minutes. for the vessel to touch bottom 850 m below the depth, where it was found.

Add to the total darkness on board, the emergency systems are unresponsive and the crew’s hunch that they are rapidly descending beyond the overwhelming depth of the submarine.

“These hazards do not make the difference between wartime and peacetime so the risk is omnipresent every time a submarine goes to sea.”