October 14, 2016:
After several years of debate and other delays the United States has approved the sale of MK-48 torpedoes to Taiwan. These will cost nearly four million dollars each and are intended for use against Chinese ships. This sale and growing nervousness about the expanding capabilities of the Chinese Navy led to a change of attitude in the United States and the West in general. That means Taiwan will also obtain the needed cooperation for expanding its submarine force by moving forward with their IDS (Indigenous Defense Submarine) program. That means building the subs in Taiwan, with a lot of foreign parts and technical advice. The first of these IDS subs won’t enter service until 2026.
Technically these Mk-48s are for Taiwan’s only two modern subs; a pair of Hailung class boats built for Taiwan in Holland and operational since the late 1980s. These 2,500 ton boats are armed with twenty torpedoes and Harpoon missiles (launched from the torpedo tubes.) These two boats are undergoing an upgrade and refurbishment that won’t be done until 2020 but will enable these two subs to remain in service for another 15 year. These two subs are being upgraded to handle the Mk-48 and new versions of the submarine launched Harpoon anti-ship missiles. .
Taiwan currently has four submarines. Two are World War II era American Guppy class subs that have been in service since 1945. These are used only for training and are increasingly difficult and expensive to maintain. Despite that the crews work hard to keep these museum pieces looking good and still useful.
Until 2016 Taiwan was having a hard time getting the United States or anyone else help them with IDS. None of the European shipyards that specialize in this sort of thing would help as they feared economic retaliation from China. The United States had not built a diesel electric sub since the 1950s. But since 2011 Taiwan did compile a lot of useful information on costs and the more reliable (resistant to Chinese threats) suppliers. These suppliers are now a lot less reluctant. It also turned out that a lot of American manufacturers could produce components for diesel electric subs even though most of their regular work is for nuclear boats. But aside from the nuclear propulsion, a sub is a sub and the American were willing to supply Taiwan.
Taiwan wanted eight new diesel-electric boats, preferably with AIP (air independent propulsion). This would drive the price up to nearly a billion dollars a boat. Building them in Taiwan can also be done more quickly with assistance from other nations threatened by Chinese naval power. India, Japan and South Korea all build subs and have local suppliers willing to provide Taiwan with components and technical assistance. While European firms won't sell Taiwan submarines they are apparently less reluctant to quietly sell components and training.
The MK-48 entered service in 1971 as the Mod 1 and has been continually upgraded since then. TheMK-48 is a 533mm (21 inch), 1.7 ton weapon with a range of up to 74 kilometers (at 50 kilometers an hour) and a top speed of 102 kilometers an hour (at a range of 38 kilometers). The MK-48 can be controlled from the sub via wire guidance and has onboard sonar to assist in finding targets and avoiding underwater obstacles. There are numerous electronic devices on board to get around countermeasures. The MK-48 has a 295 kg (650 pound) warhead and uses a proximity fuze. Maximum depth is about 800 meters. The MK-48 is already used by the U.S. Navy as well as Brazil, Australia, Canada and the Netherlands.
Since World War II only three submarine launched torpedoes have been used in combat to sink something. Only one was launched by a nuclear sub (a British boat). The other two were launched by Pakistani and North Korean diesel electric subs. No MK-48 has ever been used in combat.