The ''Admiral Pereira da Silva'' class of frigates, also known as Admiral-class frigates, were in the service of the

Portuguese Navy The Portuguese Navy ( pt, Marinha Portuguesa, also known as ''Marinha de Guerra Portuguesa'' or as ''Armada Portuguesa'') is the naval branch of the Portuguese Armed Forces which, in cooperation and integrated with the other branches of the Por ...

between 1966 and 1985. The class was based on the of the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

. The three ships of the

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differently ...

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 An empire is a "political unit" made up of several territories and peoples, "usually created by conquest, and divided between a dominant center and subordinate peripheries". The center of the empire (sometimes referred to as the metropole) ex ...

and was financed by the United States via the

Mutual Defense Assistance Program The Mutual Defense Assistance Act was a United States Act of Congress signed by President Harry S. Truman on 6 October 1949. For US Foreign policy, it was the first U.S. military foreign aid legislation of the Cold War era, and initially to Euro ...

. Financial problems prevented them from ever being modernised and they were deleted in 1989.

Design and description

By the 1960s, Portugal retained an extensive empire and the vast majority of the

'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 s. They were funded in the United States as hulls DE-1039, DE-1042 and DE-1046 under the

. The vessels were modified for service in tropical climates for service within the empire. Rated as frigates by the Portuguese Navy, they measured

long overall __NOTOC__ Length overall (LOA, o/a, o.a. or oa) is the maximum length of a vessel's hull measured parallel to the waterline. This length is important while docking the ship. It is the most commonly used way of expressing the size of a ship, and ...

with a

beam Beam may refer to: Streams of particles or energy * Light beam, or beam of light, a directional projection of light energy ** Laser beam * Particle beam, a stream of charged or neutral particles **Charged particle beam, a spatially localized g ...

of and a standard

draught Draft, The Draft, or Draught may refer to: Watercraft dimensions * Draft (hull), the distance from waterline to keel of a vessel * Draft (sail), degree of curvature in a sail * Air draft, distance from waterline to the highest point on a vessel ...

of and a maximum draught of . The frigates had a

standard displacement The displacement or displacement tonnage of a ship is its weight. As the term indicates, it is measured indirectly, using Archimedes' principle, by first calculating the volume of water displaced by the ship, then converting that value into wei ...

of and at full load. They had a complement of 166 including 12 officers. The ''Admiral Pereira da Silva''-class ships were propelled by a propeller on a single shaft turned by a

De Laval Karl Gustaf Patrik de Laval (; 9 May 1845 – 2 February 1913) was a Swedish engineer and inventor who made important contributions to the design of steam turbines and centrifugal separation machinery for dairy. Life Gustaf de Laval was born at ...

geared turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbi ...

creating . It was powered by steam from two

Foster-Wheeler Foster Wheeler AG (formerly Foster Wheeler Inc.) was a Swiss global engineering conglomerate with its principal executive offices in Reading, UK and its registered office in Baar, Canton of Zug, Switzerland. Foster Wheeler was added to the NASDA ...

boilers creating of pressure at . This gave the frigates a maximum speed of . They carried of fuel oil giving them a range of at . The vessels were primarily designed for

anti-submarine warfare Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are typi ...

(ASW). They were armed with two twin-mounted /50-caliber

dual-purpose gun A dual-purpose gun is a naval artillery mounting designed to engage both surface and air targets. Description Second World War-era capital ships had four classes of artillery: the heavy main battery, intended to engage opposing battleships and ...

s, with one

turret Turret may refer to: * Turret (architecture), a small tower that projects above the wall of a building * Gun turret, a mechanism of a projectile-firing weapon * Objective turret, an indexable holder of multiple lenses in an optical microscope * ...

forward and one aft. In the "B" position forward, the frigates mounted two four-barrelled Bofors anti-submarine rocket launchers. The ''Admiral Pereira da Silva''s also mounted two

depth charge thrower A depth charge is an anti-submarine warfare (ASW) weapon. It is intended to destroy a submarine by being dropped into the water nearby and detonating, subjecting the target to a powerful and destructive hydraulic shock. Most depth charges use ...

s and two triple Mk 32 ASW torpedo tubes for

Mark 44 torpedo The Mark 44 torpedo is a now-obsolete air-launched and ship-launched lightweight torpedo manufactured in the United States, and under licence in Canada, France, Italy, Japan and the United Kingdom, with 10,500 being produced for U.S. service. It ...

es. ''Admiral Pereira da Silva''-class frigates were equipped with Mark 63

fire-control system A fire-control system (FCS) is a number of components working together, usually a gun data computer, a Director (military), director, and radar, which is designed to assist a ranged weapon system to target, track, and hit a target. It performs ...

s. They were also fitted with MLA-1B search, Type 978 tactical and SPG-34 fire control

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

s. Th three ships of the class were equipped with different

sonar Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, measure distances ( ranging), communicate with or detect objects on ...

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 A towed array sonar is a system of hydrophones towed behind a submarine or a surface ship on a cable. Trailing the hydrophones behind the vessel, on a cable that can be kilometers long, keeps the array's sensors away from the ship's own noise sou ...

and DUBA-38 sonar.

Ships

Construction and career

All three ships were constructed in Portugal. 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. They were intended to be replaced by Dutch s but Portugal acquired the s instead.

Notes

Citations

References

* * * * * *

External links

''Dealey''-class ocean escorts
at Destroyer History Foundation {{Dealey class destroyer escort * Frigate classes Ships built in Portugal