Chang Bogo class

   Up to the 1980s the South Korean navy, faced with the threat of North Korean aggression largely through the agency of conventional submarines and small surface ships, concentrated its efforts on the deployment of ex-US surface warships and the development of its overall capability to operate more advanced vessels. The process began to bear fruit toward the end of the 1980s, when a number of more advanced vessels were ordered.

   Among the new types were the service's first submarines, which were of the West German U-209 class in its Type 1200 subvariant, which was ordered as the Chang Bogo class with a diving depth of 250 m.

   The first order placed late in 1987 covered three boats, one to be completed by Howaldtswerke of Kiel in Germany and the other two by Daewoo at Okpo in South Korea from German-supplied kits. There followed additional three-boat orders placed in October 1989 and January 1994 for boats of South Korean construction and the entire class comprises the Chang Bogo, Yi Chon, Choi Muson, Pakui, Lee Jongmu, Jeongun, Lee Sunsin, Nadaeyong and Lee Okki. The boats were laid down in the period between 1989 and 1977, launched in the period between 1992 and 2000, and commissioned in the period from 1993 to a final hand-over in 2001.

   The South Korean boats are generally similar to Turkey's six Atilay-class submarines, and emphasis is therefore placed on the installation of German sensors and weapons. Using the swim-out discharge method (resulting in reduced noise levels) from eight 533-mm (21-in) tubes all located in the bows, the latter comprise 14 SystemTechnik Nord (STN) SUT Mod 2 torpedoes, which are wire-guided weapons with active/passive homing and the ability to carry a 260-kg HE warhead out to a maximum range of 28 km at 23 kts or a shorter range of 12 km at a speed of 35 kts. The boats can also carry 28 tube-laid mines in place of the torpedoes. The older boats are being upgraded from a time early in the 21st century, and although details are currently unclear, it is believed that the modernization will include a hull stretch to the Type 1400 length of some 62 m with surfaced and submerged displacements of about 1 455 and 1 585 tons respectively, provision for tube-launched UGM-84 Harpoon missiles to enhance the boats capabilities against surface ships, and possibly the addition of a towed-array sonar for a superior capability for the detection of submerged submarines.