The usual way to catch a submarine is to send another submarine after it, or a frigate, or a helicopter dragging a sonar array through the water. All of it costs a fortune, and all of it puts a crew in harm’s way doing one of the slowest, most thankless jobs in any navy. South Korea has spent the better part of a decade building a way around that: a robot that does the hunting itself, runs on the same hydrogen power that keeps a real submarine submerged, and can stay down for a month with nobody aboard.<\/p>\n
It’s called the ASWUUV, short for anti-submarine warfare unmanned underwater vehicle, and it’s been built by Hanwha Systems together with the country’s Agency for Defense Development. The prototype is already in the water. That part isn’t new, and the company has never pretended a robotic sub-hunter would ship overnight. What is new is where the idea is headed.<\/p>\n
In December, Hanwha agreed to co-develop a separate line of cheap underwater drones for the U.S. Navy, which tells you the undersea-autonomy business South Korea has been quietly working on at home now has a buyer across the Pacific.<\/p>\n
Start with the machine, because the size is the first thing that throws people. The full-scale mockup Hanwha first rolled out in 2019 suggested a vehicle up to 10 meters long. The thing that actually got built and demonstrated is smaller: roughly 7 meters (about 23 feet) and 9 tons. That still lands it in the “large displacement” class of underwater drone, but it’s closer to a minibus than the bus you’re probably picturing.<\/p>\n
The clever part isn’t the hull, though. It’s what’s inside it. Most underwater drones run on batteries, which is fine until you want one to loiter in contested water for weeks instead of hours. The ASWUUV carries a hydrogen fuel cell instead, the same family of air-independent power that lets modern diesel-electric submarines stay submerged far longer than the boats they replaced.<\/p>\n
Hanwha built that piece with Bumhan, the company that already supplies the air-independent propulsion for South Korea’s frontline submarines, and which says it became, back in 2018, the second outfit in the world after Siemens to get a hydrogen fuel cell working underwater. Bolt that into a drone and the endurance numbers stop looking like a robot’s and start looking like a submarine’s.<\/p>\n
According to the specs reported from its sea trials by Naval News<\/a>, the drone can dive to 300 meters (about 980 feet), cruise at up to 10 knots, and stay under for 30 days. To find what it’s looking for, it carries an active sonar in the nose and two flank-array sonars running down its sides, one set to ping and listen, the other to listen quietly.<\/p>\n The Agency for Defense Development ran an operational demonstration off the southern port of Tongyeong in 2022, where the drone moved on its own and conducted anti-submarine searching and tracking with nobody steering it. South Korea isn’t alone in betting on hydrogen to crack the endurance problem, either. A German consortium has been pitching its own hydrogen-powered drone submarine<\/a> rated to stay under for months at a stretch.<\/p>\n None of this is happening in a vacuum. South Korea is building a robotic submarine hunter because it lives next to one of the largest submarine fleets on the planet. Estimates put North Korea’s fleet at roughly 70 boats. Most of them are old, small, and noisy by modern standards, which sounds reassuring right up until you remember what an old, small, noisy submarine is still capable of doing.<\/p>\n In March 2010, the South Korean corvette ROKS Cheonan broke in half and sank, killing 46 sailors. A multinational investigation concluded the ship was hit by a torpedo fired from a North Korean midget submarine. Pyongyang has always denied responsibility. Either way, the lesson Seoul took from it was blunt: the cheapest, quietest boats in the neighborhood are the ones you can least afford to lose track of, and chasing them with crewed ships and aircraft around the clock is expensive and dangerous. A drone that can sit in the water for a month, listening, is a way to keep watch over the approaches without burning out a frigate crew or putting one in the wrong place at the wrong time.<\/p>\n A single robot, however clever, doesn’t win an anti-submarine fight by itself. The way the ROK Navy describes the ASWUUV, it’s one node in a wider web. The drone is meant to work alongside surface drones (uncrewed boats), other underwater vehicles, and sensors on crewed warships, all feeding the same picture. The technical term for that is multistatic anti-submarine warfare, and the plain version is this: one platform pings, several others listen from different angles, and a hostile submarine that might slip past a single sonar has a much harder time hiding from a spread of them.<\/p>\n The crewed half of that web is already taking shape. South Korea is building its newest submarines, the 3,600-ton KSS-III Batch-II boats, with lithium-ion batteries and vertical launch cells for ballistic missiles, and Naval News reports<\/a> the navy expects those submarines to operate the ASWUUV alongside them. It’s the same class of boat Hanwha is currently pitching to build for Canada<\/a>. The drone itself is planned to enter ROK Navy service around 2030. Its design is open-architecture and can vary its operating depth, which is the engineering way of saying Hanwha built it to be upgraded and re-tasked rather than locked to one configuration. Whether it ever carries a weapon, the company hasn’t said. For now its job is to find and follow, and hand the target off to something that can finish the job.<\/p>\n Here’s where the timing gets interesting. The same expertise South Korea has been pouring into the ASWUUV is now being exported, and the most striking customer is the U.S. Navy. In December, Reuters reported<\/a> that Hanwha and a Rhode Island startup called Vatn Systems agreed to jointly develop low-cost autonomous underwater drones for the American fleet. These aren’t 7-meter sub-hunters.<\/p>\n They’re small, torpedo-shaped machines priced around $75,000 each, the kind you build in the thousands rather than the dozens, aimed squarely at the Pentagon’s push for cheap, expendable autonomous systems to offset China’s numbers in the Pacific.<\/p>\n “We believe this partnership makes a lot of sense providing that solution to the Navy,” Michael Coulter, the chief executive of Hanwha Defense USA, told Reuters. It’s part of a broader run. Hanwha’s U.S. arm has separately teamed with an American firm on much larger autonomous surface vessels, and the company has fielded interest in its uncrewed boats from Greece, Australia, Poland, and Estonia. The big hydrogen sub-hunter is the prestige project; the cheap swarm drones are the volume business. Both run on the same bet, the same one that has China testing underwater drones the size of crewed submarines<\/a>: that the future of fighting under the water belongs to machines you don’t have to crew.<\/p>\n The honest caveat is that the ASWUUV isn’t in service yet, and a prototype that moves on its own in a 2022 demonstration is not the same as a fleet of them patrolling the Yellow Sea. The 2030 date is a plan, not a delivery receipt, and nobody outside Hanwha and the South Korean navy has seen what a production version can really do against a submarine that’s actively trying not to be found. But the direction is hard to miss. The country that learned to build submarines from a German shipyard forty years ago is now building the robots meant to hunt them, on hydrogen, and finding people willing to pay for the technology long before the first one ever fires a shot.<\/p>\n","protected":false},"excerpt":{"rendered":" The usual way to catch a submarine is to send another submarine after it, or a frigate, or a helicopter … <\/p>\nThe threat it was built for is parked next door<\/h2>\n
One drone is the easy part. The network is the point.<\/h2>\n
Hanwha is selling the same idea across the Pacific<\/h2>\n