Admiral Magalhães Correia underway
Class overview
Name	Admiral Pereira da Silva class
Builders	Lisnave - Lisbon ENVC - Viana do Castelo
Operators	Portuguese Navy
Preceded by	Pacheco Pereira class
Succeeded by	João Belo class
Built	1962–1968
In commission	1966–1989
Planned	3
Completed	3
Retired	3
General characteristics
Type	Frigate
Displacement	1,914 t (1,884 long tons)
Length	95.9 m (314 ft 8 in)
Beam	11.18 m (36 ft 8 in)
Draught	5.33 m (17 ft 6 in)
Propulsion	2 × Foster-Wheeler boilers 1 × De Laval geared turbine 15,000 kW (20,000 shp) 1 shaft
Speed	27 knots (50 km/h; 31 mph)
Range	3,220 nmi (5,960 km; 3,710 mi) at 15 knots (28 km/h; 17 mph)
Complement	166
Sensors and processing systems	Mark 63 fire-control system
Armament	2 × 76 mm (3 in) guns 2 × triple 533 mm (21 in) torpedo tubes 2 × 375 mm (14.75 in) anti-submarine rocket launchers 2 × depth charge throwers

The Admiral Pereira da Silva class of frigates, also known as Admiral-class frigates, were in the service of the Portuguese Navy between 1966 and 1985. The class was based on the Dealey-class destroyer escort of the United States Navy. The three ships of the class were built in Portugal, at the Lisnave shipyards and the shipyards of Viana do Castelo. The construction of the ships was part of the effort of Portugal to expand its fleet in the face of unrest in the empire and was financed by the United States via the Mutual Defense Assistance Program. Financial problems prevented them from ever being modernised and they were deleted in 1989.

By the 1960s, Portugal retained an extensive empire and the vast majority of the Portuguese Navy's warships were dedicated to patrolling its waters. However, in that decade the empire saw unrest and invasion and the navy was expanded to meet those threats. Three ships were ordered from Portuguese shipyards to a modified design of the American Dealey-class destroyer escorts.^[1] They were funded in the United States as hulls DE-1039, DE-1042 and DE-1046 under the Mutual Defense Assistance Program.^[2][3] The vessels were modified for service in tropical climates for service within the empire.^[2] Rated as frigates by the Portuguese Navy, they measured 95.9 metres (314 ft 8 in) long overall with a beam of 11.18 m (36 ft 8 in) and a standard draught of 4.3 m (14 ft 1 in) and a maximum draught of 5.33 m (17 ft 6 in). The frigates had a standard displacement of 1,450 tonnes (1,430 long tons) and 1,914 t (1,884 long tons) at full load.^[4] They had a complement of 166 including 12 officers.^[2][4]

The Admiral Pereira da Silva-class ships were propelled by a propeller on a single shaft turned by a De Laval geared turbine creating 15,000 kilowatts (20,000 shp). It was powered by steam from two Foster-Wheeler boilers creating 2,100 kilopascals (300 psi) of pressure at 454 °C (850 °F). This gave the frigates a maximum speed of 27 knots (50 km/h; 31 mph). They carried 400 t (390 long tons; 440 short tons) of fuel oil giving them a range of 3,220 nautical miles (5,960 km; 3,710 mi) at 15 knots (28 km/h; 17 mph).^[2]

The vessels were primarily designed for anti-submarine warfare (ASW).^[5] They were armed with two twin-mounted 3-inch (76 mm)/50-caliber dual-purpose guns, with one turret forward and one aft.^[a] In the "B" position forward, the frigates mounted two four-barrelled Bofors 375 mm (14.75 in) anti-submarine rocket launchers.^[2][4] The Admiral Pereira da Silvas also mounted two depth charge throwers and two triple 324 mm (12.75 in) Mk 32 ASW torpedo tubes for Mark 44 torpedoes.^[2][6]

Admiral Pereira da Silva-class frigates were equipped with Mark 63 fire-control systems. They were also fitted with MLA-1B search, Type 978 tactical and SPG-34 fire control radars. Th three ships of the class were equipped with different sonar to reduce frequency interference. Admiral Pereira da Silva was given SQS-30, Admiral Gago Coutinho was given SQS-31 and Admiral Magalhães Correia was given SQS-31. All three vessels mounted SQA-10A variable depth sonar and DUBA-38 sonar.^[2][3]

All three ships were constructed in Portugal.^[2] After they entered service, the Portuguese Empire was disassembled beginning in the 1970s and the Portuguese economy suffered as a result. This prevented the ships from ever receiving their planned refits and saw maintenance issues increase over their careers.^[1][7] They were intended to be replaced by Dutch Kortenaer-class frigates but Portugal acquired the Vasco da Gama-class frigates instead.^[8][9]

• Oslo-class frigate - Norwegian ship class based on US Dealey class

• Blackman, Raymond V. B., ed. (1972). Jane's Fighting Ships 1972–73. London: Sampson Low, Marston & Company. OCLC 28197951.
• Couhat, Jean Labayle, ed. (1976). Combat Fleets of the World 1976/77: Their Ships, Aircraft, and Armament. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-183-8.
• Couhat, Jean Labayle, ed. (1986). Combat Fleets of the World 1986/87. Annapolis, Maryland: Naval Institute Press. ISBN 0-85368-860-5.
• Friedman, Norman (1995). "United States of America". In Chumbley, Stephen (ed.). Conway's All the World's Fighting Ships 1947–1995. Annapolis, Maryland: Naval Institute Press. pp. 544–633. ISBN 1-55750-132-7.
• Lyon, Hugh & Chumbley, Stephen (1995). "Portugal". In Chumbley, Stephen (ed.). Conway's All the World's Fighting Ships 1947–1995. Annapolis, Maryland: Naval Institute Press. pp. 317–322. ISBN 1-55750-132-7.
• Moore, John, ed. (1982). Jane's Fighting Ships 1981–82 (85th ed.). London: Jane's Publishing Incorporated. ISBN 0-86720-617-9.

Wikimedia Commons has media related to Almirante Pereira da Silva class frigates.

• Dealey-class ocean escorts at Destroyer History Foundation