Once launched, Taiwan’s new Mark 48 torpedo will search for its target at a top speed of 102 kilometers per hour over a range of as much as 50 kilometers
Despite China’s efforts to keep Taiwan from acquiring attack submarines, the island nation is on track to finish building its first indigenously made attack submarine in September of this year. If everything goes according to schedule, the diesel-electric submarine will start sea trials around February next year, with final delivery expected in the first half of 2025.
This 70-meter-long submarine will serve as the prototype of between nine to 11 subs that Taiwan plans to produce as part of an ambitious and secretive development program. Apart from two 1940s-era subs that it uses for training, Taiwan currently fields two active diesel-electric attack subs that were built in the Netherlands and entered service in 1987. These two Zwaardvis-class submarines are starting to show their age and are currently being upgraded, but it is clear that Taiwan would soon need to put new subs into service to bolster its underwater capabilities and eventually replace its two aging Dutch subs.
According to the Global Taiwan Institute, the new submarine reportedly borrows much of its shape and layout from its Zwaardvis-class boats, although it does have a number of visible external modifications. The new prototype also features a number of external and internal improvements, such as a pressure hull that can withstand the higher pressures of a greater maximum diving depth because it is made of locally-produced HSLA-80 high-strength low-alloy steel. HSLA-80 has a substantially higher yield strength than the Fe-510 steel with which Taiwan’s two Zwaardvis boats were built. In addition, as Taiwan’s navy is upgrading its aging Zwaardvis boats with photonics masts, it is assumed that the new boats would also feature photonics masts.
A global panel of experts told Reuters that Taiwan’s new indigenous submarines would join its two Zwaardvis-class boats — renamed the “Sea Dragon” class by Taiwan — to form a deadly threat that could badly damage an invasion fleet by sinking many troop carriers and warships as they make their way to Taiwan from China.
The vessels could also be deployed in the deep waters east of Taiwan, where they would sink enemy warships to help keep the island nation’s east-coast ports open, which would enable Taiwan’s allies to deliver emergency supplies during a conflict. Analysts also told Reuters that the new submarines would exploit one of the PLA’s few weak points — the fact that it still lags behind the U.S. and its allies when it comes to advanced anti-submarine warfare capabilities. Their mere presence in the waters around China would force the PLA to conduct continuous anti-submarine operations. As Japan’s retired Vice Admiral Tatsuhiko Takashima puts it: “A torpedo’s firepower is much greater than missiles or guns.”
Taiwan started looking at ways to build its own modern subs in 2017. The U.S. couldn’t provide diesel-electric submarines to Taiwan, as it has for the past few decades only built its own top-secret nuclear-powered submarines. Other nations did not dare to offend China by selling subs to Taiwan, so Taiwan’s only option was to use clandestine methods to buy sub-building secrets and to put together a global team of experts to develop its own subs.
Now that this development project, called the Indigenous Defense Submarine (IDS) project, is getting ready to give birth to its first baby, Taiwan has to ensure that it gets modern torpedoes to replace the aging torpedoes it bought for the two Sea Dragon subs in the 1980s. As the deal to buy the two Dutch subs apparently did not include the German-made AEG SUT 264 wire-guided torpedoes that were standard on such subs, Taiwan had to buy 200 of these torpedoes from an Indonesian company that produced them on license.
To replace its aging SUT torpedoes, Taiwan got permission in 2017 from the U.S. Congress to buy 46 of America’s modern Mark 48 Mod 6 AT heavyweight torpedoes. Originally scheduled for delivery in 2028, the U.S. has now fast-tracked the delivery date of these torpedoes to 2025.
The AT in the new torpedo’s name stands for “advanced technology” because it’s upgraded periodically with new technologies. With a diameter of 21 inches (53.3 centimeters), the Mark 48 is compatible with Taiwan’s existing two subs as well as its under-construction IDS subs — although the existing subs are currently undergoing electronic upgrades to program the torpedoes during combat. The torpedo is 5.8 meters long and weighs 1.7 tons, which includes the 295-kilogram high-explosive warhead.
The Mod 6 AT uses the same sonar, guidance control and electrical system as the standard Mark 48 torpedo, as well as its quieting technology. Like the SUT torpedo, the Mark 48 Mod 6 can be controlled via a physical wire, but it also has the option of operating autonomously. In addition to the standard Mark 48 technology, the Mod 6 AT variant also features sonar improvements that work with an advanced signal processor for improved low-Doppler target detection in search volumes larger than 1.6 billion cubic meters of seawater.
Once launched, this large torpedo will search for its target at a top speed of 102 kilometers per hour over a range of as much as 50 kilometers — although this maximum range can only be achieved at a cruising speed of 74 kilometers per hour. The new torpedo’s top speed makes it 60 percent faster than the old SUT torpedo, and its maximum range is 25 percent longer.
Taiwan’s military said that new upgrades to the Mark 48 torpedo will make it quieter during the launch process, which would make it more difficult for the target vessel to detect its sonar signals. The military added that each of the planned new IDS subs would be able to carry 18 of the new torpedoes and an undisclosed number of submarine-launched Harpoon anti-ship missiles, which are launched via a sub’s standard torpedo tubes.
As mentioned above, the Mark 48 Mod 6 AT torpedo can be launched from as far as 50 kilometers from the target. After launching, it homes in on the acoustic signature of the target vessel. The torpedo is designed to detonate under the target, at which point its 295-kilogram high-explosive warhead creates a powerful pressure wave that can easily break the keel of large warships, thereby destroying the target’s structural integrity and causing it to sink rapidly.