German SeaHake Torpedo Deal Casts Shadow Over DRDO’s WGHWT Programme

Gemini generated image 

 

Under a Teaming Agreement signed on March 10, 2026, ThyssenKrupp Marine Systems (TKMS), through its Atlas Elektronik segment, will transfer SeaHake mod4 heavyweight torpedo technology to Hyderabad-based VEM Technologies.

The transfer of technology (ToT) covers software licences and intellectual property required for manufacturing, integration, and potential future upgrades of the torpedoes in India.

According to the The Times of India (ToI), VEM would be responsible for the procurement of raw materials, fabrication, manufacturing, and final assembly. Atlas Elektronik will transfer torpedo technology along with the required software licences to facilitate production.

According to VEM representatives, the Atlas Elektronik partnership will enable the company to participate in the production chain of advanced naval weapon systems. The latest pact formalises the next phase of cooperation in torpedo development and production programmes.

VEM has been a Defence Research and Development Organisation (DRDO) partner for the development of the MPATGM since 2015. The company is an Aeronautical Development Agency (ADA) partner in the development of the AMCA. It builds the centre fuselage for the Tejas Light Combat Aircraft as a Hindustan Aeronautics Limited (HAL) partner. It produces the Ku-band seeker for the Astra Mk‑1 developed by DRDO’s Research Centre Imarat (RCI). It also manufactures the Stabilised Electro-Optical Sight (SEOS)—a two-axis panoramic sight designed to provide surveillance capability under both static and mobile conditions—developed by Dehradun-based Instruments Research & Development Establishment.

The current VEM–TKMS teaming could eventually spawn a joint venture that will focus on supplying heavyweight torpedoes for the Indian market and may also explore export opportunities in the future.

SeaHake Torpedo

The SeaHake mod4 (also known as DM2A4) can be deployed from both warships and submarines. Powered by an electric motor, it has a maximum speed of 50 knots and a maximum range exceeding 27 nautical miles. SeaHake’s modular battery system allows configurable range-and-speed trade-offs. It can operate at depths of up to 600 m.

The SeaHake employs advanced fibre-optic wire guidance with active/passive sonar homing and autonomous modes that allow it to operate effectively in cluttered or countermeasure-heavy environments.

It features a 260 kg PBX explosive warhead (equivalent to 460 kg of TNT) equipped with magnetic and contact fuzes for versatile detonation.

DRDO's WGHWT

VEM’s tie-up with Atlas Elektronik is likely aimed at offering an alternative to the submarine-launched wire-guided heavyweight torpedo that DRDO is developing, named WGHWT.

Like the SeaHake, the WGHWT has a maximum speed of 50 knots, a maximum range of 27 nm, a maximum operating depth of 600 m, and features electric propulsion. It carries a 250 kg high-explosive warhead.

The WGHWT is a derivative of the Varunastra heavyweight torpedo designed and developed by DRDO for use by Indian Navy warships. Varunastra has been in operational use since 2023.

Varunastra HWT

Varunastra is a warship-launched anti-submarine torpedo featuring low-drift navigation systems, acoustic homing, advanced acoustic countermeasure capabilities, and autonomous guidance algorithms. It has a maximum speed of 40 knots and a maximum operating depth of 600 m. It has a wide look angle capable of tracking silent targets.

Varunastra is too large to be fitted on a submarine and is also a generation behind contemporary torpedo technology.

As already mentioned, the WGHWT relies on wire guidance and likely features active-passive acoustic homing inherited from Varunastra.

A critical upgrade that makes the WGHWT more advanced than Varunastra is the use of a Ring Laser Gyro (RLG) inertial navigation system, which serves as a fallback to satellite navigation (SATNAV) at depths where satellite signals cannot penetrate.

The WGHWT is capable of autonomous navigation, but the fibre-optic cable link allows the operator to manually steer the torpedo toward the target’s “blind spot” or even abort the attack after launch. Varunastra lacked these advanced features.

DRDO has so far showcased WGHWT prototypes, but the torpedo remains under development.

It is likely that VEM has teamed up with Atlas Elektronik to plug a possible gap between the Indian Navy’s operational requirement and the eventual induction of the WGHWT.

Black Shark Advanced (BSA) Torpedoes

In December 2025, the Indian Navy placed an order for 48 Black Shark Advanced torpedoes with WASS Submarine Systems, a subsidiary of Italian major Fincantieri, for use on its Kalvari (Scorpene) class submarines.

Deliveries under the €200 million contract are scheduled to take place between 2028 and 2030.

Besides the delivery of torpedoes, the scope of the agreement includes launching networks for Scorpène-class submarines, as well as maintenance equipment and a full package of spare parts to ensure long-term operational readiness and sustainment.

The BSA is already in operational service with the Italian Navy and six other navies worldwide.

The BSA procurement is considered an interim measure to plug a critical capability gap. The Indian Navy requires more than 200 additional torpedoes, which it plans to procure through indigenous design and development or through foreign design with indigenous manufacturing under Transfer of Technology (ToT).

Conclusion

It is likely that the foreign-vendor-developed BSA (WASS, Italy) and SeaHake (TKMS/VEM Technologies) will compete with the DRDO-developed WGHWT for the contract to supply the Indian Navy with additional heavyweight torpedoes to meet emerging requirements.

The TKMS–VEM Technologies teaming agreement envisages production of as many as 500 torpedoes annually for the Indian Navy.

Besides Project-75 Scorpène submarines, indigenously manufactured torpedoes will arm Project-75I submarines, as well as the 12 indigenous SSKs to be developed under Project-76 and the six SSNs planned under Project-77.

It is important to note that SeaHake software will be licensed to VEM Technologies. As such, VEM will remain dependent on Atlas Elektronik for future improvements.

As things stand, the WGHWT likely lacks the stealth and versatility of SeaHake. For example, SeaHake features low-noise pump-jet or skewed propellers that reduce acoustic signature. It is also more versatile, as it can be used by both warships and submarines.

However, it is likely that through continued development DRDO’s WGHWT will eventually catch up with the sophistication of SeaHake.

DRDO AIP Plug: Late, But a Leap for Project-76 Indigenous Submarine Design

AIP Energy Module & Submarine Plug Diagram by Gemini

DRDO is reportedly poised to deliver its indigenously developed Air Independent Propulsion (AIP) plug in time for integration with INS Khanderi during its scheduled refit in 2026–27.

INS Khanderi is the second Kalvari-class (Project-75, Scorpene) submarine inducted into the Indian Navy (IN). It was commissioned on September 28, 2019.

The Indian Navy inducted six Kalvari-class Scorpene submarines under Project-75 between 2017 and 2024. Originally, it was planned to integrate DRDO-developed AIP plugs—designed to facilitate extended submerged endurance—into all Kalvari-class boats. However, the DRDO plug was not ready in time for installation on the first boat, INS Kalvari.

AIP Development Landmarks and Timeline

In June 2023, DRDO signed a contract with L&T to provide two AIP system modules for Kalvari-class submarines.

Under the contract, the Naval Materials Research Laboratory (NMRL), a DRDO laboratory, transferred AIP technology to L&T. The AIP modules are manufactured, integrated, and undergo factory acceptance trials at L&T’s AM Naik Heavy Engineering Complex in Surat.

The AIP modules, also called Energy Modules (EMs), are integrated into the AIP plug, which is then retrofitted into the submarine during refit. The refit will also include equipping the boat to launch DRDO-developed heavyweight torpedoes.

In December 2025, DRDO was expected to deliver the EM for integration with the plug that will be inserted into INS Khanderi during its refit.

“The system has undergone extensive shore-based trials and has met the required benchmarks. Integration work on the second submarine is expected to be completed before December 2026,” Times Now reported, quoting sources.

The submarine will need to undergo extensive trials following installation of the AIP plug, since the dimensions and buoyancy characteristics of the boat will change.

Sea trials are reportedly expected to commence between July and August 2027, with the full refit process expected to conclude by early 2028, the sources added.

Characteristics of the DRDO-Developed AIP

The DRDO-developed AIP uses phosphoric acid fuel cell (PAFC) technology.

A fuel cell converts chemical energy from a fuel into electricity through a chemical reaction between positively charged hydrogen ions and oxygen (or another oxidizing agent).

1. Several fuel cell types exist, including:
2. Alkaline Fuel Cell (AFC)
3. Proton Exchange Membrane Fuel Cell (PEMFC)
4. Direct Methanol Fuel Cell (DMFC)
5. Molten Carbonate Fuel Cell (MCFC)
6. Phosphoric Acid Fuel Cell (PAFC)
7. Solid Oxide Fuel Cell (SOFC)

A PAFC uses phosphoric acid (H₃PO₄) as the electrolyte. Hydrogen gas (H₂) is used as the fuel at the anode, while oxygen (O₂) from air is supplied at the cathode.

PAFC fuel cells offer several advantages over other fuel cell types. They provide greater fuel flexibility and are more tolerant of fuel impurities. They can operate using reformed hydrocarbon fuels such as methanol or even biogas.

PAFC operating temperatures (150–200°C) are relatively high. As a result, they generate steam as a byproduct in addition to electrical power for propulsion. The steam can be utilized for other onboard heating requirements, raising overall operating efficiency to as high as 70%.

INS Khanderi

DRDO AIP Critical for Project-76 Submarines

Successful integration of the DRDO AIP plug will not only augment the capabilities of Project-75 submarines but will also facilitate finalization of the design of Project-76 submarines.

Under Project-76, India has embarked on an ambitious design, development, and manufacturing program to deliver 12 next-generation diesel-electric attack submarines (SSKs) to the Indian Navy.

Project-76 is envisaged as the logical successor to the foreign-designed Project-75 (French Scorpène) and the upcoming Project-75I (Most likely German Type-214) programs.

Project-76 was initiated in late 2023 when the Indian Navy’s Warship Design Bureau (WDB) received formal authorization to begin the preliminary design phase.

In early 2024, the MoD allocated initial funding for the indigenous development of two pivotal enabling technologies for modern submarines: AIP systems and advanced lithium-ion batteries. As noted earlier, AIP offers increased submerged endurance, while lithium-ion batteries provide higher discharge rates and faster charging compared with traditional lead-acid batteries.

Project-76 aims for an unprecedented 90–95% indigenous content, including the Combat Management System (CMS), sonar suites, and periscopes.

Development Timeline

L&T is confirmed to be part of the design process along with the Navy’s Directorate of Naval Design (Submarine Design Group) (DND-SDG).

L&T’s credentials in submarine construction are impressive and extend beyond the development of the AIP plug for Project-75 submarines. The company previously carried out detailed engineering and hull construction for the Arihant-class SSBNs. It also designed and developed the SOV-400 Midget Submarine, a 400-tonne special operations vessel for commandos.

Additionally, L&T designed and built the Submarine Escape Training Tower (SETT) facility in Visakhapatnam, which is used to train naval crews in emergency escape procedures.

P-76 Progress

In September 2025, a senior L&T official reportedly stated that the design phase of the submarine could be completed by 2026–27.

As of March 2026, the project has moved into the detailed design phase. The Indian Navy is currently finalizing the Staff Requirements to ensure the P-76 can act as a bridge between conventional SSKs and nuclear-powered attack submarines (SSNs) being built under Project-77.

Initially, six submarines are proposed to be built. The first submarine could be delivered in six to seven years, with all six delivered within ten years.

As mentioned earlier, follow-on orders are likely to meet the Indian Navy’s expanding requirements.

P-76 Specifications

The P-76 submarine is envisioned as a 3,000-tonne class vessel, roughly 50% larger than the current Kalvari class.

It will feature a fully indigenous AIP system and incorporate advanced lithium-ion batteries, both designed and developed by DRDO in collaboration with L&T.

The submarine will be armed with indigenously developed torpedoes as well as torpedo-tube-launched anti-ship and land-attack cruise missiles.

 

When MR-SAM Is Available, Why Import Shtil-1?

Gemini generate image of a Shtil-1 interceptor launch from a IN warship

The MoD recently inked contracts worth ₹5,083 crore for the ALH Mk-III (MR) and VL-Shtil missiles.

According to the MoD press release on the Vertical Launch Shtil missiles:

“The contract for the procurement of Surface-to-Air Vertical Launch Shtil missiles and associated missile holding frames, valued at ₹2,182 crore, has been signed with JSC Rosoboronexport, Russian Federation. The acquisition is intended to substantially enhance the air defence capabilities of frontline warships against a wide spectrum of aerial threats.

The system will reinforce the layered air defence architecture onboard Indian Navy platforms by providing rapid-reaction, all-weather engagement capability and improved survivability in contested maritime environments.”

About Shtil-1

The Shtil-1 is an area air defence missile system developed by Russia's Almaz-Antey for light warships.

The Shtil-1 uses the 9M317ME semi-active radar homing (SARH) missile, a specialised naval variant of the missile used in the land-based Buk-M2 air defence system. The 9M317ME is a single-stage solid-fuel interceptor with folding fins to fit inside compact VLS canisters. During mid-course, the missile uses inertial guidance, 

The choice of a SARH system represents a well-considered engineering trade-off that prioritises cost, missile size, and terminal power over the “fire-and-forget” convenience of an Active Radar Homing (ARH) system like the MR-SAM.

The use of SARH enables strong target illumination using the ship’s high-power fire-control radars (such as the MR-90 Orekh). In contrast, an ARH missile relies on a small, battery-powered radio frequency (RF) transmitter, resulting in weaker target illumination.

SARH seekers are significantly cheaper and simpler to mass-produce than ARH seekers. Since a ship might need to carry 24–36 missiles, the cost savings are substantial.

By removing the radar transmitter and its associated cooling and power requirements from the missile, engineers can either reduce missile size or use the additional space for a larger warhead or more fuel.

An ARH missile is more susceptible to jamming due to its low-power RF transmitter. Since a SARH seeker is passive (it only listens), it is harder for a target to jam the missile directly. The target would have to overpower the ship’s high-power radar illuminating it.

However, SARH systems have limitations. They work best for shorter-range engagements. The ship must maintain line of sight to the target to keep it illuminated. This makes it difficult to engage sea-skimming missiles that are over the radar horizon.

Additionally, the further the target is from the ship, the weaker the reflected illumination becomes, in accordance with the inverse square law.

Shtil-1 Antecedents

The Shtil-1 system replaces the older Shtil/Uragan systems that used a single-arm rail launcher. In contrast, the Shtil-1 employs a modular, below-deck cellular Vertical Launch System (VLS).

This allows 360-degree omnidirectional defence without the need to rotate a heavy launcher toward the target.

Shtil-1 Performance

The system is capable of a high rate of fire, with the ability to launch a missile every 2–3 seconds.

The Shtil-1 is designed to intercept a wide spectrum of aerial threats, including supersonic aircraft, helicopters, drones, and high-speed anti-ship missiles. It can engage targets at ranges from 3.5 km to 50 km and at altitudes ranging from as low as 5 metres (sea-skimming missiles) up to 15 km.

A single installation can reportedly track and engage up to 12 targets simultaneously, making it effective against swarm or saturation attacks.

The Shtil-1 was developed for Project 11356R (Admiral Grigorovich-class) frigates in the Russian Navy. It currently equips Indian Navy Tushil-class frigates (Project 11356 derivatives).

Several Indian Navy warships previously equipped with Shtil/Uragan systems are now being fitted with Shtil-1 systems. These include:

Batch I & II Talwar-class frigates — INS Talwar, INS Trishul, INS Tabar, INS Teg, INS Tarkash, and INS Trikand — originally equipped with the 3S-90 single-arm launcher located forward of the bridge, carrying 24 missiles.

Delhi-class destroyers — INS Delhi, INS Mysore, and INS Mumbai — which feature two 3S-90 single-arm Shtil/Uragan launchers (one forward and one aft) firing 9M38M1 missiles. These are now slated for, or currently undergoing, Shtil-1 upgrades as part of their mid-life refits; they are also being equipped with improved Fregat-M2EM radars to handle contemporary saturation threats.

Shivalik-class stealth frigates — INS Shivalik, INS Satpura, and INS Sahyadri — originally fitted with the single-arm Shtil/Uragan launcher and now slated for, or undergoing, Shtil-1 upgrades like the Delhi class destroyer.

Conclusion

The Shtil-1 is one of the two principal area air defence systems fitted on Indian Navy warships, the other being the Israeli-Indian MR-SAM (Barak-8).

The Shtil-1 is both robust and cost-effective. As an evolution of the Buk family, it has an creditable operational track record. It relies on Semi-Active Radar Homing (SARH), wherein the ship continuously illuminates the target with dedicated radars until impact. The high power of the ship’s radar mitigates the effects of RF stealth techniques. The system’s relative simplicity and the availability of multiple vertical launch cells enable a high rate of fire.

In contrast, the MR-SAM is a more sophisticated and more expensive fire-and-forget system using Active Radar Homing (ARH). It offers a superior range of approximately 70 km and higher manoeuvrability due to its dual-pulse motor. The Shtil-1 (using the 9M317ME missile), by comparison, employs a more traditional single-stage, single-pulse solid-fuel motor.

The MR-SAM is better suited to high-value capital warships, while the Shtil-1 provides a more cost-effective solution for smaller platforms such as frigates.