Bay class frigate

HMS Bigbury Bay in 1945
Class overview
Name:	Bay class
Builders:	Charles Hill & Sons Henry Robb Blyth Dry Dock Smiths Dock William Pickersgill Harland & Wolff
Operators:	Royal Navy  Portuguese Navy  Finnish Navy
In commission:	1945–1971
Completed:	26
General characteristics
Type:	Frigate
Displacement:	1,600 long tons (1,626 t) standard 2,530 long tons (2,571 t) full
Length:	286 ft (87 m) p/p 307 ft 3 in (93.65 m) o/a
Beam:	38 ft 6 in (11.73 m)
Draught:	12 ft 9 in (3.89 m)
Propulsion:	2 Admiralty 3-drum boilers, 2 shafts, 4-cylinder vertical triple expansion reciprocating engines, 5,500 ihp (4,100 kW)
Speed:	19.5 knots (36.1 km/h; 22.4 mph)
Range:	724 tons oil fuel, 9,500 nmi (17,600 km) at 12 knots (22 km/h)
Complement:	Frigates: 157 Despatch vessels: 160 Survey ships: 133
Sensors and processing systems:	Type 285 fire control radar Type 291 air warning radar Type 276 target indication radar High Frequency Direction Finder (HF/DF) IFF transponder
Armament:	4 × QF 4 inch Mark XVI guns on 2 twin mounting HA/LA Mk.XIX 4 × 40 mm Bofors A/A on 2 twin mounts Mk.V 4 × 20 mm Oerlikon A/A on 2 twin mounts Mk.V 1 × Hedgehog 24 barrel A/S projector 2 rails and 4 throwers for 50 depth charges

The Bay class was a class of 26 anti-aircraft (A/A) frigates built for the Royal Navy under the 1943 War Emergency Programme during World War II (one of which was cancelled and six completed as despatch vessels or survey ships). They were based on the hulls of incomplete Loch class anti-submarine (A/S) frigates.

In 1959 and 1961, four frigates of the class (Bigbury Bay, Burghead Bay, Morecambe Bay and Mounts Bay) were transferred to the Portuguese Navy. Between 1966 and 1968, based in Mozambique, these ships were part of the Portuguese naval deterrent force against the Royal Navy Beira Patrol. In 1966 the Portuguese Navy also bought the survey vessel Dalrymple which served until 1983.

The Bay class made use of the hull, machinery, lattice mast and superstructure of incomplete Loch class frigates. The armament was altered to suit them to the A/A role, with twin QF 4 in Mark XVI guns fore and aft in mounts HA/LA Mark XIX fitted with remote power control (RPC), controlled by a rangefinder-director Mark V carried on the bridge and fitted with radar Type 285 for range taking. Due to a shortage of supply of 4-inch (10 cm) guns and mountings, many ships had these removed from laid up V and W class destroyer "WAIR" conversions and Hunt class destroyers that were constructive total losses. A pair of Mark V "utility" mounts for twin 40 mm Bofors guns were sited amidships, each with its own predictive Simple Tachymetric Director (STD) for fire control. The A/A armament was completed by a pair of mounts Mark V for twin 20 mm Oerlikon guns, carried in the bridge wings. Later, the Oerlikons were replaced with single mounts Mark VII for Bofors guns, a further pair of which were added amidships on raised platforms. For A/S use, a Hedgehog projector was carried on the fo'c'sle and the quarterdeck carried two racks and four throwers for up to 50 depth charges.

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