The 3,600-ton Seo Hui, the second submarine in South Korea’s Jang Bogo-III Batch-II program, is scheduled to enter the water Tuesday ahead of a planned 2028 Navy delivery.
The ceremony is planned for Hanwha Ocean’s shipyard in Geoje, about 330 kilometers southeast of Seoul, according to a joint statement from the Navy and Defense Acquisition Program Administration (DAPA).
Seo Hui is the second boat in the Jang Bogo-III Batch-II program. Its predecessor, Jang Young-sil, was launched in October 2025. Yonhap, in a report carried by The Korea Herald, said Batch-II boats are longer and heavier than the 3,000-ton Batch-I submarines now in service.
The Yonhap report said the newer boats have an expanded vertical launch system for submarine-launched ballistic missiles and an advanced sensor suite. It also described Seo Hui’s diesel-electric system, which combines lithium-ion batteries with air-independent propulsion to keep the vessel submerged longer.
The report cited North Korea’s naval expansion as the strategic backdrop, including the 5,000-ton Kang Kon and Choe Hyon destroyers. Seo Hui is scheduled for delivery to the Navy in 2028 after operational tests.
