After being frustrated in its persistent efforts to acquire additional modern submarines from abroad over the past three decades, Taiwan embarked on an ambitious plan to design, develop, and build its own diesel-electric submarines several years ago. There is now a broad consensus in Taiwan that submarines, by virtue of their greater survivability and significant deterrent potential, are essential for the island’s defense. Given Taiwan’s geography, submarines play a critical role in defending sea lanes of communication (SLOCs) for the country’s economy and energy security, as well as the threat of maritime blockade and amphibious invasion. Known as the Indigenous Defense Submarine (IDS), the program is being implemented as a top national priority and at a nearly breakneck pace. The last point is especially noteworthy, given Taiwan’s lack of prior experience in submarine design and existing submarine industrial base. Especially as the program is afforded very substantial resources as well as policy latitude.
Program Requirement, Cost, and Schedule
The IDS is being developed to meet a Taiwan Navy requirement for an ocean-going submarine of 1,500-2,000 (standard) displacement. The boat would be capable of anti-surface (ASuW), anti-submarine (ASW), mine warfare, intelligence, surveillance & reconnaissance (ISR), and special operations missions.
The contract for the 4-year design phase was awarded in December 2016 to the quasi-state-owned (42.5 percent) CSBC Corporation, at a contract value of US$86 million (NT$2.59 billion). Work began in early-2017, with the Preliminary Design completed in March 2018, and the Contract Design to be delivered by March 2019. The detail design is slated for completion by the end of 2020.
This is a remarkably aggressive schedule at a relatively low cost, not least because it is the first time Taiwan has tried to develop an ocean-going submarine (1,500-2,000-ton nominal displacement) and lacks direct technical assistance from an experienced foreign submarine builder/design house.
The budget for the construction of the lead submarine amounts to US$1.64 billion (NT$49.36 billion) over the 7-year period spanning from 2019 through 2025. The unit cost is inflated due to inclusion of the capital investment needed for construction of the new submarine construction yard inside CSBC’s main complex at Siaogang, in southern Kaohsiung. The total cost for the program, as originally envisioned, could amount to US$13.3 billion (NT$400 billion), with up to eight submarines to be built indigenously over a 25-year period.
Although awarded as a “design-build” contract to CSBC, design work for the IDS program is actually subcontracted out to the Ship and Ocean Industries R&D Center (SOIC) and overseen by Taiwan Navy’s Naval Shipbuilding Development Center (NDSC). All together, there are currently several hundred naval architects and marine engineers working on the indigenous submarine design.
Secrecy and Scandal
The program is highly classified, and little reliable information has been officially released, particularly with regards to the design, choice of primary equipment and sources of foreign technical assistance. In fact, the IDS program is so tightly held that the project manager reports directly to the Navy Commander-in-Chief and then to the Presidential Palace, effectively bypassing the Ministry of National Defense. This has raised questions with regards to the chain of command and proper oversight.
The only accidental disclosure that has emerged in the form of an alleged scandal over the selection of the design consultant for the prime contractor, the quasi-state owned CSBC International Shipbuilding Corp. Gavron Limited, which is a small, newly established company headed by former British submarine officers and domiciles in Gibraltar, was chosen over much larger, far more established European and North American firms in 2017. Even though one of the former partners of the agent who supposedly brokered the (US$20 million/NT$600 million) consulting deal publicly claimed that the brother of Taiwan Navy’s Commander-in-Chief was involved in the transaction—the Navy and MND have both denied any illegality.
IPR Issues Complicate US Program Support
To this date, the platform development and engineering efforts have not received any technical assistance that is officially sanctioned by the United States government. This is ostensibly due to Washington’s uncertainty over intellectual property rights of the IDS concept design. Taiwan is reportedly basing its indigenous submarine hull design and general layout on the Dutch Zwaardvis Mk 2, two of which were built by Wilton-Fijenoord shipyard in the 1980s (these submarines are known as the “Jian Lung/Sword Dragon” class in Taiwan service). As a part of that deal, Taiwan was provided with a (supposedly only partial) technical data package, to facilitate in-country maintenance support for the boats.
The Dutch Zwaardvis class design was developed from the US Barbel class, which was built in the mid-1950s, incorporating the then newly successful streamlined “teardrop” or “body of revolution” hull form and the single-shaft design of USS Albacore. Such a design concept ensured high underwater speed, as well as significant usable internal volume. Both of these features made the basic Zwaardvis design a desirable starting reference for Taiwan in developing its own submarine design.
Design and Construction
The IDS reportedly borrows heavily from the Zwaardvis Mk 2/Sword Dragon design concept, albeit with a number of visible modifications. These include a sloping bow design featuring top-bottom asymmetry and an X-form rudder system (instead of the original cross-shaped rudder on the Zwaardvis Mk 2). The modified bow and forward casing design, similar to that found on the Japanese Oyashio class and Soryu class, is typically associated with the use of conformal arrays instead of a cylindrical bow sonar. However, it is unclear if this is also the case on the new IDS design. The use of X-form rudders aims to improve underwater maneuverability, reduce collision risk when landing, and lower noise from propeller flow interactions.
According to Rear Admiral Shao Wei-Yang (邵維揚), Director of NSDC and the de facto IDS chief designer, the new submarine has different operational requirements than the Zwarrdvis Mk 2/Sword Dragon and would feature different patrol range/endurance and acoustic silencing performance. The IDS should have greater maximum designed diving depths, in view of the planned use of locally-produced HSLA-80 high-strength low-alloy steel in pressure hull construction. The HSLA-80 has substantially higher yield strength than the Fe-510 steel with which Taiwan’s Zwaardvis Mk 2 boats were built (550 MPa vs. 355 MPa).
Furthermore, since Taiwan Navy is introducing a photonics mast (or optronic periscope) upgrade as part of the Life Extension Program (LEP) for its two Sword Dragon class (Zwaardvis Mk 2) submarines, it is reasonable to expect that photonics mast technology would also be employed on the IDS.
CSBC, together with SOIC and NSDC, have scoured the world market for critical systems and technology, especially HM&E (hull, mechanical, and electrical) equipment, components and engineering support, for which the United States has not offered active support. Even though the CSBC/SOIC/NSDC team appears confident that they will be able to obtain all the equipment and components necessary for building the design they are developing, export licensing for certain major equipment items remains less than absolutely certain as of this writing. As a possible fallback, Taiwan may fund the trial manufacturing of a number of critical systems by local industry. Moreover, Taiwan is also exploring domestic sources for such applications as fuel cells and lithium-based battery technology for submarine propulsion. However, it is not certain if equipment produced by local sources could be ready and sufficiently mature in time for the fit out on the first submarine, which is scheduled to begin construction in 2020/2021.
In April 2018, the United States approved marketing license and technical assistance agreement for Lockheed Martin and Raytheon to work with Taiwan on providing combat system solutions for the IDS program. It is understood that Raytheon will be providing the sensor systems (sonars, etc.), while Lockheed Martin will be responsible for the combat management system integration.
Details of the IDS sensor suite are yet unknown, although it is expected to consist of a bow sonar, flank arrays, and an intercept array group. Adoption of a sloping bow shape, as supported by circumstantial image evidence, suggests the possible use of a different bow sonar than the original cylindrical-type array on the Zwaardvis Mk 2, but this remains to be confirmed.
Towed array will not be included in the baseline configuration, even though the United States has issued export license for a thin-line towed array to Taiwan in support of the IDS project. The advanced towed array is capable of long-range detection and tracking of surface and underwater targets, with significant potential for intelligence collection as well as war fighting applications. Its exclusion on the prototype is driven by the desire to mitigate design risks, especially in the context of the tight development schedule.
There will also be a search radar, an electronic support measure (ESM) system, datalink, and various communication systems (including satellite communications), all of which already exist on Taiwan’s Sword Dragon class (Zwaardvis Mk 2) submarines.
The indigenous submarine is expected to be armed with heavyweight torpedoes, submarine-launched anti-ship missiles, and, if required, sea mines. The United States had previously approved the sale of Mark 48 Mod. 6AT torpedoes as well as Sub-Harpoon missiles to Taiwan.
The IDS hull design has been undergoing hydrodynamic tank tests at an eminent model basin establishment in Europe. The Taiwan Navy is in the process of selecting an international firm to serve as its consultant to help evaluate the contract design in the upcoming Critical Design Review (CDR), which is scheduled for March 2019.
With IDS both a top priority military requirement and the centerpiece of President Tsai Ing-Wen’s defense industry policy, there is tremendous pressure for the program to succeed and remain on (its very tight) schedule. As such, there are concerns that political pressure could undermine the rigor normally associated with CDR. Moreover, continued uncertainties with respect to the ability to secure export licenses for critical equipment and components could greatly complicate efforts to actually build the submarine, even if the design is deemed satisfactory by an honest CDR process.
Even though Rear Admiral Shao has testified to the Legislative Yuan that export permits for all essential equipment are already at hand, there remains uneasiness among insider experts (who wish to remain anonymous) about the design team’s ability to secure all necessary interface control documentation (ICD) for all major system components in the immediate future.
The Taiwan Navy is in the process of selecting consultants to help evaluate the IDS contract design developed by the CSBC/SOIC/NSDC team. Consulting services specifically pertain to technical analysis of the submarine’s electrical system, rudder system, safety assurance system, vibration mitigation reduction/shock protection measures, hull/hydrodynamic noise analysis, composite material sail, and construction planning.
Five companies from Europe, North America, and India are competing for the contract, worth US$7.6 million in total. A British firm and a North American entity appear to be in final contention. However, again, local experts quietly voice concerns about potential conflict of interest whereby the design consultant and the prospective Navy consultant may both ultimately be represented through the same ownership.
Given its lack of prior experience in the design, construction, and testing of modern submarines of this complexity, Taiwan sorely requires assistance in program management to help guide the builder through the construction and testing processes. Indeed, the need for suitable underwater testing facilities could present a whole other challenge for the IDS project. There are very few oceanographically and acoustically suitable as well as sufficiently secure sites near Taiwan that could be used as an underwater range to test the new submarine(s).
Finally, Taiwan would require robust technical assistance if serious platform or system problems should emerge during construction or sea trials. As such, Taiwan should begin discussions with the United States with respect to a possible framework for undersea warfare (submarine) cooperation/assistance, not dissimilar to what Australia was able to develop with the United States in the wake of the Collins class experience.
The main point: Indigenous Defense Submarine (IDS) is a top-priority program in which Taiwan has been willing to resort to extraordinary measures and commit enormous resources, even though critical challenges remain, and Taiwan would ultimately benefit from US assistance.