Hanwha Ocean completes major overhaul of ROK Navy’s KSS-II submarine

April 8, 2026, by Fatima Bahtić

Hanwha Ocean has completed a 16-month maintenance, repair, and overhaul (MRO) program on the Republic of Korea Navy’s KSS-II (Type 214) submarine Yu Gwan-sun.

The 1,800-ton submarine, originally built and delivered in 2017, underwent an extensive, full-spectrum overhaul involving the disassembly, servicing, and replacement of critical systems from bow to stern. According to the company, the project was delivered on schedule through optimized planning and execution, including a reduced sea trial period.

The successful completion of the project underscores Hanwha Ocean’s growing credibility in lifecycle support for advanced submarines, a capability expected to strengthen its position in upcoming global opportunities such as the Canadian Patrol Submarine Project (CPSP).

The Yu Gwan-sun is the sixth of nine KSS-II submarines built under the second phase of South Korea’s multi-stage submarine acquisition program.

South Korea receives sixth KSS-II submarine ‘Yu Gwan-sun’

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Measuring 65 meters in length with a displacement of 1,800 tonnes, KSS-II submarines are equipped with advanced indigenous systems, including long-range submarine-launched cruise missiles, torpedoes, and mines.

These platforms also feature automatic simultaneous target tracking and sophisticated torpedo guidance and detection systems, enhancing their operational effectiveness in complex maritime environments.

The KSS-II class builds upon the earlier KSS-I (Chang Bogo-class) submarines, based on German Type 209 designs, and represents a key step in South Korea’s plan to field a fleet of up to 27 submarines across three development phases.

With the Yu Gwan-sun now returned to operational service following its overhaul, the program highlights the ROK Navy’s commitment to maintaining a modern and capable undersea fleet.