The Blackwood class displaced 1,180 long tons (1,200 t) at standard load and 1,456 long tons (1,479 t) at deep load. They had an overall length of 310 feet (94.5 m), a beam of 33 feet (10.1 m) and a draught of 15 feet (4.6 m). The ships were powered by one English Electric geared steam turbine that drove the single propeller shaft, using steam provided by two Babcock & Wilcox boilers. The turbine developed a total of 15,000 shaft horsepower (11,000 kW) and gave a maximum speed of 27 knots (50 km/h; 31 mph).[1] The Blackwoods had a range of 4,500 nautical miles (8,300 km; 5,200 mi) at 12 knots (22 km/h; 14 mph). Their complement was 140 officers and ratings.[2]
The ships were armed with three Bofors 40 mm guns in single mounts. The mount on the quarterdeck was later removed as it was unusable in heavy seas. They were equipped with two triple-barrelled Limbo Mark 10 anti-submarine mortars. The Blackwood-class ships had the same sonar suite as the larger Whitby-classfrigates where the Limbo mortars were controlled by three sonars, the Type 174 search set, Type 162 target-classification set and the Type 170 'pencil beam' targeting set to determine the bearing and depth of the target.[3]
On commissioning, Keppel joined the Second Training Squadron, based at Portland Harbour.[5] She paid off for an extended refit in March 1958, during which her hull was strengthened as a result of operating experience of ships of the class in heavy seas.[6][7] In September 1960, Keppel returned to the Portland Training Squadron, and from June 1963 to April 1964 served with the Fishery Protection Squadron.[8]
In February 1973, Keppel was reduced to reserve, joining the Standby Squadron at Chatham.[8][5] She was listed for disposal when a boiler explosion on sister ship Hardy, serving with the 2nd Frigate Squadron at Portland, caused Keppel to return to active service to replace Hardy in July 1975.[5][9]Keppel remained with the 2nd Frigate Squadron, serving in the training role, until November 1976.[8][5]
She was again placed on the disposal list in 1977 and was scrapped at Sittingbourne in 1979.[8][10]
Critchley, Mike (1986). British Warships Since 1945: Part 5: Frigates. Liskeard, UK: Maritime Books. ISBN0-907771-13-0.
Friedman, Norman (2006). British Destroyers and Frigates, the Second World War and After. Annapolis, Maryland: Naval Institute Press. ISBN1-86176-137-6.
Gardiner, Robert; Chumbley, Stephen & Budzbon, Przemysław (1995). Conway's All the World's Fighting Ships 1947–1995. Annapolis, Maryland: Naval Institute Press. ISBN1-55750-132-7.
Marriott, Leo (1983). Royal Navy Frigates 1945–1983. Shepperton, Surrey, UK: Ian Allan. ISBN0-7110-1322-5.