South Korea's Hanwha unveils Seo Hui, first submarine merging AIP and lithium-ion power
Hanwha Ocean gave reporters a look inside the Seo Hui, the second Jangbogo-III Batch-II submarine, showcasing its hybrid air-independent propulsion and lithium-ion battery system. The vessel also features upgraded combat and sonar suites and improved crew accommodations.
At Hanwha Ocean’s Geoje shipyard in South Gyeongsang Province, officials opened the interior of the Seo Hui, the second Jangbogo-III Batch-II submarine, to the press. The 3,600-ton vessel, about 89 metres long, is larger than the earlier Dosan Ahn Chang-ho-class boats and incorporates roughly 80% locally sourced components. Its combat management and sonar systems have been upgraded for better data processing, target detection and land-attack capability, and it features more horizontal and vertical launch tubes to carry torpedoes, guided missiles and submarine-launched ballistic missiles.
The standout feature is a hybrid propulsion system that pairs Hanwha Ocean’s air-independent propulsion with lithium-ion batteries from Hanwha Aerospace, which the company says provides the longest submerged endurance for a diesel-electric submarine. Crew comfort has been improved, with each of the approximately 50 personnel receiving an individual berth and expanded washroom and shower areas. Construction proceeds in a new 12,000-square-metre special ship plant, where autonomous mobile robots and smart cranes assist with material handling, and the adjacent hull sections are being assembled before final welding. Nearby, the fifth Ulsan-class Batch-III frigate Pyeongtaek is undergoing dockside trials ahead of its planned delivery in December 2027.
Why it matters
The submarine introduces a novel hybrid propulsion that could boost South Korea's naval stealth and endurance capabilities.
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