The KSS-III (Korean Submarine-III) or Dosan Ahn Changho-class is a series of diesel-electric attack submarines currently being built for the Republic of Korea Navy (ROKN), jointly by Hanwha Ocean and HD Hyundai Heavy Industries (HHI). The KSS-III is the final phase of the Korean Attack Submarine program, a three-phased program to build 27 attack submarines for the ROKN, between 1994–2029.
The KSS-III initiative consists of the development of nine diesel-electric attack submarines, capable of firing submarine-launched ballistic missiles (SLBM), to be built in three batches, between 2014–2029.
A total of three submarines of the first batch of the series have been launched, with the first submarine, , being commissioned on 13 August 2019. The second ship, , was commissioned on 20 April 2023.
Design
Background
The design of the KSS-III was jointly designed by Daewoo Shipbuilding & Marine Engineering (now Hanwha Ocean) and Hyundai Heavy Industries (now HD Hyundai Heavy Industries) - two of South Korea's largest shipbuilding enterprises; preparations for the design began in 2007. The KSS-III is the largest submarine built in Korea and the first submarine designed with domestic technology, unlike the KSS-II submarine (Son Won-il-class submarine) previously produced in cooperation with Howaldtswerke-Deutsche Werft (HDW).
Dosan Ahn Chang-ho class, the first 3,000-ton submarine designed through the KSS-III program, achieved a 76 percent localization rate, twice as high as the previously license-built KSS-II submarine. The development process adopted a design process using digital mock-up simulation for the first time in Korea, and the hull was made of HY-100 alloy steel to withstand high pressure of deep water. Although the size of the submarine is larger than that of the existing KSS-II submarine, the noise is minimized by applying non-acoustic stealth technologies such as acoustic anechoic coating and elastic mounts. The submarine's interior is made up of large and small pipes measuring 85 km in total length and has 127 types of acoustic and electronic equipment embedded in.
The first ROKS Dosan Ahn Changho designed in the KSS-III program was designed as a system development process using experimental technologies to demonstrate South Korea's independent submarine building capabilities, but the ROKS Ahn Mu is the first submarine to be built and commissioned through an official mass production process. SS-085 Ahn Mu successfully passed 125 items of builder test, 208 items of harbor acceptance test, and 90 items of sea acceptance test during the trial run process from January 2020 to April 2023. It also includes key features such as VHF marine communication system, passive linear array sonar, torpedo acoustic counter measure, underwater radiated noise level, electric propulsion motor, which are improved from the previous SS-083 Dosan Ahn Changho.
Batch-I
The Batch-I series is the first phase of the KSS-III program - consisting of the construction of three attack submarines - with the first two to be built by Daewoo Shipbuilding & Marine Engineering (DSME) and the third one to be built by HHI.
The Batch-I design possesses a length of , with a breadth of and a draught of - with a displacement of while surfaced and while submerged; they are the first submarines with a displacement of 3,000 tonnes to ever be built by South Korea. According to DSME, over 76% of the submarine's components were procured from within South Korea.
The Batch-I design has an estimated speed of about while surfaced, and while submerged - and possesses a cruising range of around , at economic speed, along with a crew complement of 50. The design further incorporates an indigenously-designed fuel-cell powered air-independent propulsion (AIP) module - which enables the submarine to conduct long-distance underwater operations for up to 20 days. The PH1 fuel cell module developed by Bumhan Industries is also the second hydrogen fuel cell used in submarines in the world after Siemens' fuel cell.
The design accommodates six Korean Vertical Launching System (K-VLS) cells, located behind the submarine's sail - for carrying six Hyunmoo 4-4 submarine-launched ballistic missiles (SLBM), along with six forward-firing torpedo tubes, located at the bow. Coincidentally, the KSS-III is the first ever AIP-equipped attack-submarine, capable of launching submarine-launched ballistic missiles.
Batch-II
The Batch-II series constitutes the second phase of the KSS-III program - and is noted to possess multiple improvements in terms of design, armament and automation, over the Batch-I series.