After years of setbacks spanning construction, launch, and sea trials, the vessel has gained momentum in recent months. A successful torpedo-firing exercise in early May gave defense officials their clearest signal yet that the combat system is functioning as designed. Delivery to the navy is now expected in the second half of this year.
If the Hai Kun enters service as planned, it will mark a genuine milestone in Taiwan's pursuit of defense self-sufficiency.
But the symbolism of commissioning a first-ever domestically built submarine only tells part of the story. Measured against the operational realities of a high-intensity conflict in the Taiwan Strait — and the formidable challenges facing the seven follow-on vessels already in planning — the navy's harder tests are only just beginning.
A Capable Design Built Around a Single Priority: Getting It Done
The Hai Kun is approximately 70 meters long and eight meters wide, with an estimated displacement of between 2,500 and 3,000 tonnes. It features an X-shaped stern rudder standard among advanced contemporary submarines, and appears to draw heavily on the Dutch Zwaardvis-class design with significant modifications.
The vessel is equipped with a U.S.-made digital combat management system, active and passive sonar, MK48 Mod6AT heavyweight torpedoes, and UGM-84 Sub-Harpoon anti-ship missiles — a potent weapons suite on paper.
Yet Taiwan entered this program with no prior submarine manufacturing experience, and that constraint shaped every major decision. The navy's overriding priority was to deliver a working vessel, not an ideal one.
As a result, two features standard on most advanced conventional submarines worldwide were left out: an air-independent propulsion (AIP) system, which allows a submarine to remain submerged for extended periods without running its diesel engines, and anechoic tiles — the specialized acoustic coating applied to a submarine's outer hull to reduce its sonar signature.
Military sources speak frankly about why. The program's total budget reached NT$37.9 billion, with direct construction costs of approximately NT$25.6 billion excluding facilities and equipment. Adding AIP would have substantially increased both engineering complexity and expenditure. Omitting anechoic tiles reflected the same combination of budget pressure and technical caution.
H.I. Sutton, a submarine analyst with a well-established international profile in defense intelligence circles, has assessed the Hai Kun's design as comparatively conservative — while also characterizing the navy's approach as reasonable and understandable for a nation's first domestically produced submarine.
A Conservative Strategy Brings the Submarine to Service — at the Cost of Stealth
The navy's cautious approach will in all likelihood succeed in getting the Hai Kun commissioned. But it comes at a measurable cost to the vessel's underwater concealment capabilities.
Confidence in the Hai Kun's ability to sustain high-intensity operations in the waters around Taiwan is limited — not only among outside analysts, but within the military itself.
A navy source told Storm Media that even after the Hai Kun joins the fleet later this year — and even accounting for the high caliber of the crew in the 256th Submarine Squadron assigned to operate her — it will likely take one to two years of training and operations before the vessel can reliably transition from routine patrols to genuine combat readiness.
Without AIP, without anechoic tiles, and relying on comparatively low-capacity lead-acid batteries, the submarine's weaknesses in stealth and sustained submerged endurance cannot be compensated for by its advanced U.S. combat systems and formidable armament alone.
The operational consequences of the missing AIP system are concrete. Lead-acid batteries store limited energy, and the Hai Kun's submerged endurance at low speed falls well short of European and Japanese conventional submarines equipped with AIP or lithium-ion cells.
In a Taiwan Strait conflict scenario — where the Hai Kun would move into a designated ambush zone to engage People's Liberation Army surface vessels — the submarine could not remain submerged for extended periods. Every two to three days, it would need to ascend to snorkel depth, run its diesel engines, and recharge. That cycle would disrupt ambush operations and, more critically, expose the vessel at its most vulnerable moment.
The threat environment surrounding Taiwan makes that vulnerability especially consequential. The navy source noted that the PLA maintains a layered anti-submarine network in the waters around Taiwan: AIP-equipped conventional submarines, nuclear-powered attack submarines, fixed-wing maritime patrol aircraft, long-endurance drones with submarine detection capabilities, and surface combatants carrying active and passive sonar.
When the Hai Kun rises to snorkel depth — its diesel exhaust heat, engine noise, and protruding snorkel mast all potentially detectable — the risk of discovery by PLA sensors is substantial. A submarine caught in that exposed state, the source said, is effectively a stationary target with little prospect of survival.
No Anechoic Tiles: Why Acoustic Exposure Undermines Survivability
The absence of anechoic tiles raises a separate but equally serious concern.
Advanced nuclear and conventional submarines worldwide almost universally coat their hulls with this specialized material, which serves two functions: absorbing active sonar pulses from enemy ships and aircraft, and blocking the outward transmission of internal machinery noise. A submarine fitted with anechoic tiles can reduce an adversary's detection capability by at least 50 percent, and potentially by as much as 70 percent.
Without that protection, the Hai Kun is susceptible to detection at range by the PLA's existing active and passive sonar systems.
In submarine warfare, where the decisive advantage lies in detecting and engaging the enemy first — and then withdrawing before being engaged in return — being located by the adversary first is, as one defense source put it, effectively a death sentence.
Once the Hai Kun enters service, the navy is expected to pursue upgrades. Information circulating in defense circles suggests that anechoic tiles may be retrofitted and the lead-acid batteries eventually replaced with lithium-ion cells — improvements that would meaningfully enhance acoustic stealth and extend submerged endurance.
For the seven planned follow-on submarines, the navy has outlined a three-phase construction program spanning fourteen years: two initial vessels based on modest modifications to the prototype, three improved production-standard submarines, and two final vessels designed to incorporate the full lessons of the program and push capability to its peak.
But a defense intelligence source familiar with submarine development cautioned that this phased timeline may reflect a degree of institutional optimism that underestimates the technical obstacles ahead.
Upgrading Follow-On Vessels Is Harder Than It Sounds
The source was careful to frame his concerns not as a critique of the Hai Kun program, but as a frank assessment of unavoidable engineering realities.
The prototype's structural configuration and internal layout are already finalized, with the weight distribution of every system — including propulsion and batteries — calculated with precision. Even adding anechoic tiles to the outer hull, without modifying internal structures, would require recalculating hydrodynamic performance data and assessing whether the added weight affects submerged stability.
Replacing the lead-acid batteries with lithium-ion cells — which differ in both weight and volume — would require replacing the power management system as well, effectively necessitating a recalibration of all core parameters.
Submarine design, the source stressed, requires extremely fine tolerances between internal space and weight distribution. Miscalculations can produce catastrophic results.
A follow-on vessel that substitutes lithium-ion batteries cannot simply replicate the prototype's design — adjustments to internal structures and systems would create cascading effects throughout the hull. That risk is compounded by an existing limitation in the Hai Kun itself: because the navy was unable to procure military-grade diesel engines, the vessel was fitted with six smaller, commercially rated Swedish marine engines in a parallel arrangement. Compared to military-specification powerplants, this configuration produces more noise and offers lower reliability.
A Real Combat Platform — Within Limits
Despite the prototype's performance constraints, the unresolved engineering challenges facing the follow-on program, and the political uncertainty over future submarine budgets in a legislature currently controlled by the opposition, military sources are consistent in one assessment: the Hai Kun is a genuine combat platform that carries real strategic value.
Its very presence at sea creates ambiguity and unpredictability that would compel the PLA to divert substantial resources to anti-submarine operations — the classic "fleet-in-being" effect.
And its payload of 18 MK48 Mod6AT heavyweight torpedoes and UGM-84 Sub-Harpoon missiles constitutes a credible threat to PLA surface combatants that cannot be dismissed.
Military sources nonetheless acknowledge that given the prototype's current capabilities, the Hai Kun is best suited for ambush operations in deep water to the northeast or southwest of Taiwan, where it can leverage the strengths of its U.S.-made combat systems, sonar, and weapons.
More demanding missions — extended operations in the South China Sea, counter-blockade patrols at the edge of the first island chain, or direct submarine-versus-submarine engagements against the PLA — would likely exceed what the vessel can currently sustain.
Whether Taiwan's domestically built submarine force can eventually grow into a credible long-range sea-denial deterrent depends on a set of conditions that remain far from guaranteed: the successful completion of lithium-ion battery upgrades, engine replacement, and anechoic tile installation across the follow-on program, as well as the political will to fund it.
The Hai Kun's commissioning, when it comes, will be a hard-won achievement. What follows will be harder still. （Related： Taiwan's Hai Kun Submarine Heads Out for Critical Torpedo Test With U.S. Lease Deadline Looming ｜ Latest ）
