FF-1052 Knox-class

Summary

Description

The Knox-class frigates served as the United States Navy's principal anti-submarine warfare (ASW) vessels in the latter part of the 20th century. This class of 46 frigates was used extensively during the Cold War era, with all ships being decommissioned by 1994 after serving no more than 23 years each. These frigates are distinguished as the last U.S. Navy destroyer-type ships designed with steam turbine powerplants. Decommissioned due to cost, defense budget cuts, and the need for more advanced ASW capabilities, some Knox-class vessels continue to operate with foreign navies, notably in Egypt, Taiwan, Thailand, and Mexico.

The Knox-class originated from the intention to follow on from the Garcia-class frigates and Brooke-class missile frigates. Designed with reduced crew sizes and increased endurance, the class was based around the AN/SQS-26 sonar. Its armament initially included ASROC anti-submarine missiles, a drone helicopter, and a 5-inch gun. However, plans changed when the Navy opted for less compact powerplants, leading to lengthier and heavier ships. The cancellation of the Sea Mauler missile left the class without substantial anti-aircraft protection except the 5-inch gun. The steam plant powering each ship provided a speed of 27 knots via a single screw.

Operational history reveals that ships of the Knox class were fitted with several ASW devices and sensors, including the AN/SQS-26 low-frequency sonar and a sonar array encased in a deployable "fish." The class underwent modifications that included the addition of surface-to-air missile systems to compensate for early mission limitations. A notable upgrade was the retrofitting of hurricane bows to reduce deck wetness and protect weapons from heavy seas. Some ships also received extensions to helicopter facilities for larger manned helicopters following the unreliability of the earlier drone.

Construction of the Knox-class vessels spread across several fiscal years, with initial procurement from more than one shipyard before later orders were consolidated to Avondale Shipyards for cost-efficiency. Prefabricated modules were used to streamline the assembly process. All ships were originally designated as destroyer escorts and later reclassified as frigates in 1975.

The class saw further adaptations abroad. Spain built five modified versions known as the Baleares-class with a focus on air-defense capabilities. The Republic of China (Taiwan) received eight Knox-class ships, refitted with various combat systems and missiles for extended service life. Renamed the Chi Yang-class, these ships continued to hold a key role in Taiwan's naval strategy and are expected to be replaced by new light frigates.

Technical specifications