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British Navy HMS Sutherland Type 23 frigate begins Sea Trials after upgrade with new propulsion.
HMS Sutherland, the last remaining Type 23 frigate in service, has completed a major upgrade to its power generation system, a strategic overhaul carried out by Babcock and overseen by Defence Equipment & Support (DE&S). This modernization is part of a broader program aimed at extending the operational life of the Type 23 frigates as the Royal Navy gradually transitions to the new Type 26 and Type 31 classes. Thanks to these enhancements, these ships will remain in service until the 2030s, continuing their critical missions in anti-submarine warfare and maritime security operations.

HMS SUTHERLAND during exercises with the Japanese Navy in 2021 (Picture source: UK MoD)
Introduced in the 1990s, the Type 23 frigates have formed the backbone of the Royal Navy’s surface combat fleet. Originally designed for anti-submarine warfare in the North Atlantic, their role has expanded over time to include maritime patrols, counter-piracy missions, trade route protection, and rapid response operations. However, after more than thirty years of service, these vessels required significant upgrades to maintain their performance levels and ensure operational effectiveness in increasingly contested maritime environments. To address this, the Power Generation Machinery Upgrade (PGMU) program was launched, aiming to improve the reliability, energy efficiency, and durability of the power generation systems aboard the Type 23 frigates.
HMS Sutherland (F81), the thirteenth unit of this class, is renowned as the fastest of the Type 23 frigates, having recorded speeds of over 34 knots (63 km/h) during trials in 2004. Its primary role remains anti-submarine warfare, for which it is equipped with a low-frequency towed sonar array, capable of detecting, classifying, and tracking submarines long before they can detect the ship. It can also carry a Merlin or Wildcat helicopter, armed with torpedoes and depth charges, extending its submarine engagement range. Beyond its submarine warfare capabilities, HMS Sutherland is a versatile vessel, capable of undertaking maritime surveillance, counter-terrorism operations, illegal trafficking prevention, and escorting strategic convoys.
Built by Yarrow Shipbuilders and launched in 1996, HMS Sutherland was named in an unusual ceremony, where a bottle of Macallan whisky was used instead of the traditional bottle of champagne, reflecting its Scottish heritage and connection to the County of Sutherland. The ship’s crew of approximately 200 personnel is divided into several specialist units, including warfare, engineering, logistics, and embarked aviation. All crew members are also trained in whole-ship emergency procedures, including firefighting, damage control, and first aid.
HMS Sutherland is armed with a range of defensive and offensive systems, ensuring close-range protection and engagement versatility. It is equipped with Sea Wolf surface-to-air missiles, capable of neutralizing aerial threats at short range, and Harpoon anti-ship missiles, designed to engage enemy vessels at medium range. Its 114mm naval gun provides fire support against maritime and land targets, while Sting Ray torpedo launchers add an extra layer of anti-submarine defense. Additionally, the ship’s electronic warfare systems and missile countermeasures enhance its protection against modern threats.
Throughout its service, HMS Sutherland has distinguished itself on multiple occasions. In 2017, it was selected to escort the aircraft carrier HMS Queen Elizabeth during its maiden departure from Rosyth for sea trials, a mission that underscores the strategic importance of this frigate within the Royal Navy’s fleet. It also became the first Royal Navy warship to deploy a Wildcat helicopter in the Asia-Pacific region, showcasing the Royal Navy’s global reach and rapid deployment capabilities.
With the completion of its power generation system upgrade, HMS Sutherland becomes the last Type 23 frigate to benefit from the PGMU program. This modernization aims to optimize the performance of its diesel generators and energy management systems, improving the ship’s endurance, reliability, and operational resilience. As the Type 23s are progressively replaced by more modern units, HMS Sutherland will play a key role in the transition of the fleet, ensuring that the Royal Navy maintains a robust maritime presence, ready to meet future strategic challenges.
The ongoing sea trials will validate the integration of the new equipment and assess its performance under real operational conditions. This phase is crucial before the frigate returns to active service, where it will remain one of the cornerstones of the Royal Navy’s surface fleet until its eventual decommissioning. The completion of this modernization marks an important milestone in the lifecycle management of the Type 23 frigates, ensuring their transition to future platforms while maintaining a high level of readiness and force projection within the Royal Navy.