The KSS-III (Korean Submarine-III; Korean: 한국형 잠수함-III; Hanja: 韓國型潛水艦-III), officially called Dosan Ahn Changho class (Korean: 도산안창호급 잠수함; Hanja: 島山安昌浩級潛水艦; RR: Dosan-anchangho-geup Jamsuham) is a series of diesel-electric multipurpose attack submarines currently being built for the Republic of Korea Navy (ROKN), jointly by Hanwha Ocean and HD Hyundai Heavy Industries (HHI).[4] 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.[23]
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.[4][24]
A total of three submarines of the first batch of the series have been launched, with the first submarine, ROKS Dosan Ahn Changho, being commissioned on 13 August 2019.[2] The second ship, ROKS Ahn Mu, was commissioned on 20 April 2023.
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.[25][26] 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).[27][28]
The 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.[27][28]
The first vessel, ROKS Dosan Ahn Changho, of 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 second, ROKS Ahn Mu, is the first submarine to be built and commissioned through an official mass production process. 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 Dosan Ahn Changho.[29]
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.[30]
The Batch-I design possesses a length of 83.5 metres (273 ft 11 in), with a breadth of 9.6 m (31 ft 6 in) and a draught of 7.62 m (25 ft 0 in) - with a displacement of 3,358 tonnes (3,305 long tons) while surfaced and 3,750 tonnes (3,690 long tons) while submerged; they are the first submarines with a displacement of 3,000 tonnes to ever be built by South Korea.[31][17][32][33] According to DSME, over 76% of the submarine's components were procured from within South Korea.[33]
The Batch-I design has an estimated speed of about 12 knots (22 km/h; 14 mph) while surfaced, and 20 knots (37 km/h; 23 mph) while submerged - and possesses a cruising range of around 10,000 nautical miles (19,000 km; 12,000 mi), at economic speed, along with a crew complement of 50.[34] 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.[35][36] The PH1 cell module developed by Bumhan Industries is also the world's second hydrogen fuel cell used in submarines after Siemens' fuel cells.[10][37][38]
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 533-millimetre (21 in) forward-firing torpedo tubes, located at the bow.[39] Coincidentally, the KSS-III is the first ever AIP-equipped attack-submarine, capable of launching submarine-launched ballistic missiles.[20]
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.[40]
The Batch-II design possesses a length of 89.3 m (293 ft), with a breadth of 9.6 m (31 ft), along with an estimated displacement of around 3,600 t (3,500 long tons).[41][42] According to DSME, the Batch-II series will be equipped with "a greater level of South Korean technology" - with over 80% of the submarine's parts to be domestically sourced.[43][44]
Similar to the Batch-I, the Batch-II will also reportedly have a top speed of 20 knots (37 km/h; 23 mph) and a crew complement of 50.[41]
A notable feature of the Batch-II submarines is its lithium-ion battery technology (LiB); the Batch-II series will be equipped with lithium-ion batteries - developed by Samsung SDI (and supplied by Hanwha Defense), apart from the AIP system.[45] Compared to previous lead-acid batteries which are generally used to power other conventionally-powered submarines, the new lithium-ion batteries will reportedly allow the KSS-III to cruise at greater speeds with a greater period of underwater endurance, life-expectancy and durability.[46] Incidentally, Korea is only the second country in the world to field submarines equipped with lithium-ion batteries; the first is Japan - which utilizes lithium-ion battery technology aboard its Sōryū-class submarines.[47]
The design also incorporates ten K-VLS cells (compared to six on the Batch-I) - which are presumably to carry the Hyunmoo 4-4 ballistic missiles and the future Chonryong land-attack cruise missile.[48]
The Batch-I series is currently equipped with an assortment of different sensors and equipment, including:
On 26 December 2012 - South Korea's Ministry of National Defense (MND) contracted DSME to build the first two Batch-I submarines - at an estimated cost of USD $1.56 billion.[17] On 30 November 2016 - the MND contracted HHI to build the third submarine of the series.[30]
The construction of the first submarine began in November 2014, with a "steel-cutting" ceremony at DSME's shipyard in Okpo, South Korea[57] The submarine, christened as the Dosan Ahn Changho, was launched in an elaborate ceremony on 14 September 2018 - an event that was attended by senior representatives from South Korea's government and military, including South Korean president Moon Jae-in.[57] Dosan Ahn Changho began its sea trials in June 2019 and was commissioned into the ROKN on 13 August 2021.[57]
Work on the second submarine began - with the laying of its keel in July 2016.[30] Christened as the Ahn Mu, the submarine was launched on 10 November 2020.[58] It is scheduled to be delivered by 2022.[58]
The construction of the third and final submarine began in June 2017, at HHI's shipbuilding facility in Ulsan, South Korea.[30] Christened as the Shin Chae-ho, the submarine was launched on 28 September 2021.[59] It is scheduled to be delivered by 2024.[59]
On 11 October 2019, South Korea's Defense Acquisition Program Administration (DAPA) contracted DSME to design and build the first Batch-II submarine - at an estimated cost KRW ₩1.11 trillion.[60] On 10 September 2019, DSME was again contracted to build the second Batch-II submarine - at an estimated cost of ₩985.7 billion.[61]
The construction of the first submarine - the Lee Bong-chang, began in August 2021 and is scheduled to be delivered to the ROKN in 2026.[62] The construction of the second submarine began in December 2021 and is scheduled to be delivered to the ROKN by 2028.[63]
At the 2019 convention of the "International Maritime Defense Industry Exhibition" (MADEX), held at Busan, South Korea, DSME unveiled the DSME-2000 - a 2,000 t (2,000 long tons), diesel-electric variant of the KSS-III, as an export-oriented design for foreign navies.[64]
The DSME-2000 possesses a length of 70.3 m (230 ft 8 in) and a diameter of 6.3 m (20 ft 8 in), with a crew complement of 40, with additional space for about 10 special forces commandos.[15] The design has an estimated speed of 10 knots (19 km/h; 12 mph) while surfaced, and 20 knots (37 km/h; 23 mph) while submerged and possesses a cruising range of around 10,000 nmi (19,000 km; 12,000 mi), at cruising speed.[15]
The DSME-2000 displaces at 2,000 tonnes and is larger than South Korea's