HMS Exmouth (F84): The Frigate That Became the World's First All-Gas-Turbine Warship

Built as a Conventional Steam Frigate

HMS Exmouth was built by J. Samuel White and Company, laid down on 24 March 1954 and launched on 16 November 1955, a Blackwood-class Type 14 anti-submarine frigate, a specialised design built around the single-minded purpose of hunting Soviet submarines rather than general-purpose fleet duties.

She displaced 1,456 tons at full load, measured 310 feet in length, and was originally powered by conventional steam turbines fed by two Babcock and Wilcox boilers, producing 15,000 shaft horsepower for a top speed of 27 knots.

She commissioned on 20 December 1957, entering service as, in every meaningful respect, a fairly ordinary example of her class.

A Radical Rebuild

HMS Exmouth's real significance came a decade into her career, when she underwent a major refit beginning in 1966 that stripped out her original steam boilers and turbine propulsion system entirely, replacing them with an experimental arrangement powered solely by gas turbines.

The new system used a combined gas-or-gas, or COGOG, configuration, pairing a single Bristol Siddeley Olympus TM1 engine rated at 15,000 shaft horsepower with two smaller Bristol Siddeley Proteus engines each producing 3,500 shaft horsepower, an arrangement that allowed her to run efficiently on the smaller engines for cruising and switch to the powerful Olympus for maximum speed.

When she rejoined the fleet on 5 June 1968, HMS Exmouth had become the first ship in the world powered entirely by gas turbines, a remarkably landmark achievement in marine engineering that would go on to shape the propulsion of nearly every major Royal Navy warship built in the decades that followed, from destroyers to carriers, gas turbines having proven themselves considerably lighter, more responsive and easier to maintain than the steam plants they gradually replaced across the fleet.

Trials Across the Mediterranean

Through the 1970s, HMS Exmouth carried out extensive trials to validate all-gas-turbine propulsion under genuine operational conditions, working extensively across the Mediterranean and operating from Malta.

She proceeded as far east as Crete during these trials, making her the only Type 14 frigate ever to venture that far into the eastern Mediterranean, an unusual itinerary for a class of ship generally associated with home waters and North Atlantic anti-submarine patrols rather than distant deployments.

HMS Exmouth also served as plane guard for the carrier HMS Ark Royal during this period, standing by to rescue aircrew in the event of a flying accident, and took part in rescue operations connected to an incident involving a Soviet destroyer, though the precise details of that episode have not survived clearly in the historical record available.

Later in her career, she operated from Chatham and from the Isle of Portland as a workup support vessel, helping prepare other ships' crews for operational service, a role that put her considerable experience with novel propulsion technology to practical, if unglamorous, use.

Legacy

HMS Exmouth was broken up in 1979, closing out a career whose real significance lay not in any single dramatic action, but in the years of patient trials work that helped prove all-gas-turbine propulsion could particularly work at sea.

It is a quietly important legacy: from HMS Exmouth's experimental engine room came the propulsion architecture that would go on to power the Type 42 destroyers, the Type 22 and Type 23 frigates, and eventually the Royal Navy's modern carriers, making this unassuming Type 14 frigate a notably foundational ship in the story of postwar British naval engineering, however few people outside specialist circles ever came to know her name.