Chi Yang-class (Knox-class)

The Chi Yang-class frigates originated as second-generation anti-submarine warfare escorts, initially serving as ocean escorts before being redesignated in 1975. Following their retirement from their original fleet at the conclusion of the Cold War, eight of these vessels were transferred to the Republic of China Navy during the 1990s. These ships represent the final destroyer-type design to utilize a steam turbine power plant, a feature that has defined their operational history and subsequent maintenance requirements.

The platform is engineered primarily for anti-submarine warfare, centered on a massive bow-mounted low-frequency scanning sonar. The propulsion system utilizes two high-pressure boilers to drive a single shaft. To extend the operational utility of the hulls, several units underwent significant modification, incorporating combat systems and radars salvaged from retired destroyers. The armament is comprised of a 5-inch/54 caliber gun and a versatile eight-cell launcher capable of firing both anti-submarine rockets and anti-ship missiles. Air defense is provided by Standard missile box launchers installed around the helicopter hangar. Additional sub-surface detection and engagement capabilities include variable depth sonar, passive towed array sonar, and torpedo tubes. The integrated flight deck and hangar are configured to support anti-submarine helicopters.

Assigned to the 168 Patrol Squadron, these frigates are utilized for anti-submarine patrols. In this role, the vessels typically deploy with a mixed load of anti-ship and anti-submarine ordnance. The class has begun to undergo phased retirement as the hulls and steam plants age; one vessel was expended as a naval target in 2020, and others have been decommissioned. Due to the obsolescence of the onboard battle systems and the high cost of maintaining the aging machinery, the class is scheduled for replacement by a new generation of light frigates.