The Jang Yeong-sil is the first vessel of the improved Batch-II series, following the earlier Dosan Ahn Chang-ho-class submarines built under the KSS-III Batch-I. It is the ROK Navy’s first 3,600-ton-class submarine and is designed and constructed entirely in South Korea, with the project progressing from a contract signed in 2019 to steel cutting in 2021 and keel laying in 2023.
Now measuring approximately 89 metres in length and displacing 3,600 tons, the Jang Yeong-sil features significant upgrades in detection, stealth, survivability, and strike capabilities. The vessel is equipped with an upgraded combat system—described as its “brain”—and a more advanced sonar suite—its “eyes and ears”—to enhance information processing, target detection, and land-attack effectiveness.
The submarine uses domestically developed lithium-ion batteries, allowing longer underwater endurance, sustained high-speed operation, and reduced noise, which decreases the risk of detection during missions. Noise and vibration reduction technologies have also been applied to lower its underwater acoustic signature and improve overall stealth.
An auxiliary propulsion system has been added to improve survivability, enabling the submarine to manoeuvre even in the event of a main propulsion failure. This system strengthens its operational resilience during emergency scenarios.
The Batch-II class features an expanded vertical launch system (VLS) with ten cells, compared to six in the Batch-I vessels. It also includes twelve newly developed domestic systems, raising the number of localised components to 70 and reinforcing South Korea’s technological independence amid global export restrictions and intellectual property challenges.
The Jang Yeong-sil reflects over thirty years of South Korean submarine development, progressing through the Type 209-based KSS-I and Type 214-based KSS-II programmes. The ongoing KSS-III initiative comprises six submarines across two batches and is intended to support regional strategic deterrence.
Construction of the second Batch-II unit began in July 2024 and is expected to launch in 2026, while the third unit began in October 2024 with delivery projected around 2031. The Jang Yeong-sil will now undergo sea trials, system evaluations, and final acceptance, with official delivery to the ROK Navy set for late 2027.
