Country: United States
The Knox Class was originally designated a Destroyer Escort but this was changed in 1975 to Frigate. They were the result of United States congressional concerns over the mounting costs of the Brooke Class Missile Frigate.
The Knox-class frigates were Anti-Submarine Warfare (ASW) vessels and as such fulfilled a Protection of Shipping (POS) mission. These frigates were designed as convoy escorts and were to replace the hundreds of destroyer escorts built during the Second World War that were being disposed of in the 1960s.
The 46 vessels built in this class were produced between 1965 and 1973. These frigates represent the most successful of the second generation escort vessels built after 1945. They cruised at 22 knots on one boiler and fitted with a 5-bladed, fifteen-foot wide propeller. An additional ten ships were cancelled.
During the period 1972-1977 they were modified to accommodate the SH-2D LAMPS (Light Airborne Multi-Purpose System) helicopter during which their flight deck and hangar were enlarged.
As their primary function was anti submarine warfare it is hardly surprising the SQS-26CX bow mounted sonar dome was the design centre of the ship. This was complemented by the large ASROC launcher providing the major ASW weapon.
Modernization and equipment enhancement went on throughout their career. A variable depth sonar (SQS-35) was installed in 35 ships in the late 1970s to provide better detection capabilities against submarines operating below thermal layers. Also at this time anti-air capability was introduced with the addition of the Mk25 BPDMS Sea Sparrow launcher on the fantail in 31 ships. In the 1980s, 31 ships were fitted with the SQR-18A towed arrow system.
With the end of the Cold War those that remained in Service or the Reserve were retired as there was no longer any need for their advanced ASW capability. A number were transferred to the navies of Egypt, Taiwan, Thailand, Turkey and Mexico.