DSEI 2025: Type 26 Frigate Enhances Undersea Warfare Capabilities for High North Operations

At DSEI 2025 in London, BAE Systems and the Royal Navy highlighted the evolving capabilities of the Type 26 Global Combat Ship (GCS), with a specific focus on its undersea warfare (USW) role in contested environments such as the High North. Designed from inception for anti-submarine warfare (ASW) dominance, the Type 26 is now entering a critical phase of maturity as construction progresses and integration of key subsurface sensors accelerates.

Purpose-Built for Anti-Submarine Warfare

The Type 26 frigate—also known as the City-class—is a next-generation ASW platform being developed by BAE Systems for the Royal Navy. It replaces the aging Type 23 Duke-class frigates in their primary ASW role. With eight vessels planned (three under construction), it features a low acoustic signature hull design optimized to reduce detectability by enemy submarines.

Key to its ASW mission is an integrated sensor suite centered around:

• Ultra Electronics’ Sonar 2150: A bow-mounted medium-frequency active/passive sonar system.
• Thales CAPTAS-4: A variable depth sonar (VDS) and towed array combination offering long-range submarine detection even in complex oceanographic conditions.
• Sonobuoy processing systems: Integrated with Merlin HM2 helicopters via Link-11/Link-22 datalinks.

The CAPTAS-4 VDS is particularly relevant for operations in Arctic waters where thermoclines and ice cover can degrade traditional hull-mounted sonar performance. The ability to deploy sensors at varying depths gives commanders tactical flexibility against increasingly quiet adversary submarines such as Russia’s Yasen-M or Kilo-class platforms operating in the Barents Sea or GIUK gap.

Quiet Propulsion and Acoustic Signature Reduction

A defining feature of the Type 26 is its Combined Diesel-Electric or Gas (CODLOG) propulsion system. This configuration allows electric-only cruising at low speeds—ideal for ASW patrols—while retaining gas turbine power for high-speed sprints. The ship uses:

• A Rolls-Royce MT30 gas turbine (36 MW)
• Four MTU diesel generators powering electric motors
• A raft-mounted machinery layout to dampen vibrations

This architecture minimizes radiated noise—a critical factor when tracking submarines or avoiding counter-detection. The ship’s propeller design and hull form further reduce cavitation and flow noise.

High North Operational Context

The emphasis on undersea warfare at DSEI reflects growing NATO concern over Russian submarine activity in Arctic waters and across transatlantic sea lines of communication (SLOCs). The melting polar ice cap has opened new maritime routes while increasing competition over seabed resources. The Royal Navy has identified this region as a strategic priority under its Defence Command Paper Refresh (2023).

The Type 26’s endurance (>7,000 nautical miles), modular mission bay (capable of deploying UUVs/AUVs), and robust USW suite make it well-suited for persistent presence missions north of Norway or Iceland. Its compatibility with NATO-standard communications and data links ensures interoperability with allied navies including those operating P-8A Poseidon aircraft or FREMM-class frigates equipped with similar sonar systems.

Modular Design Enables Future Growth

The ship’s adaptable architecture allows rapid reconfiguration based on mission needs. Its flexible mission bay can support containerized payloads such as:

• Uncrewed underwater vehicles (UUVs)
• Towed decoys or acoustic jammers
• MCM modules or seabed surveillance kits

This modularity aligns with emerging concepts like Distributed Maritime Operations (DMO) and Multi-Domain Integration (MDI). As threats evolve—from seabed sabotage to autonomous underwater threats—the ability to integrate new payloads without major structural changes offers long-term relevance.

Status of Construction and Export Potential

As of Q3 2025:

• HMS Glasgow, first-in-class, is undergoing outfitting after launch at BAE’s Govan shipyard; sea trials are expected by mid-2026.
• HMS Cardiff is structurally complete; internal systems integration underway.
• HMS Belfast, third hull laid down; steel cutting began in late 2023.

The UK Ministry of Defence has committed £3.7 billion ($4.7B) for the first three units under Batch One procurement. Australia’s Hunter-class frigate program and Canada’s Canadian Surface Combatant both derive from the Type 26 baseline design but incorporate national-specific combat systems—highlighting strong export traction despite rising costs and delays reported by national audit offices in both countries.

DSEI Takeaways: A Platform Built Around Sonar Superiority

DSEI 2025 reaffirmed that unlike many multi-role surface combatants designed around air defense or strike missions, the Type 26 prioritizes acoustic dominance from keel up. Its sonar suite rivals that of dedicated SSNs while offering greater persistence via embarked helicopters like Merlin HM2 equipped with dipping sonars and torpedoes.

This focus on undersea warfare—especially in cold water environments—is not incidental but foundational to its concept of operations. As NATO shifts attention toward securing transatlantic reinforcement routes against peer adversaries with expanding submarine fleets, platforms like Type 26 will be central to maritime deterrence strategies through mid-century.