Knox-class frigate

Knox-class frigates were United States Navy warships, originally laid down as ocean escorts (formerly called destroyer escorts), but were all redesignated as frigates on 30 June 1975 in the 1975 ship reclassification plan and their hull designation changed from DE to FF.

Knox-class frigate USS Robert E. Peary (FF-1073) and the skyline of San Francisco in the background
Class overview
Preceded by: Garcia-class frigate / Brooke-class frigate
Succeeded by: Oliver Hazard Perry-class frigate
Built: 1965–1974
In commission: 1969–1994 (USN)
Planned: 55
Completed: 46
Cancelled: 9[1]
Retired: 46 (USN)
Preserved: TCG Ege (ex USS Ainsworth)
General characteristics
Type: Frigate
Displacement: 4,260 tons (full load)
Length: 438 ft (134 m)
Beam: 46 ft 9 in (14.25 m)
Draft: 24 ft 9 in (7.54 m)
Propulsion: 1 shaft, one Westinghouse steam turbine, 2 V2M boilers. total 35,000 shp (maximum)
Speed: over 27 knots (50 km/h)
Complement: 17 officers, 240 enlisted
Sensors and
processing systems:
Electronic warfare
& decoys:
Aircraft carried: One SH-2 Seasprite (LAMPS I) helicopter

Modifications were made to Joseph Hewes and subsequent ships of the class. The primary differences were slightly different arrangement of the "Officer's Country" staterooms with additional staterooms in the 01 level instead of the open deck between the boat decks. The stateroom on the port side under the bridge was designated as a "flag" stateroom, with additional staterooms for flag staff when serving as a flagship. These ships have been referred to as the Joseph Hewes-sub-class


The 46 ships of the Knox class were the largest, last and most numerous of the US Navy's second-generation Anti-submarine warfare (ASW) escorts. The lead ship of the class was USS Knox (FF-1052), laid down 5 October 1965 and commissioned on 12 April 1969, at Todd Shipyards in Seattle.[2] Planned as the follow-on to the twin 5-inch gun armed Garcia-class frigates and the Tartar missile-equipped Brooke-class frigates, their initial design incorporated the prior classes' pressure-fired boilers in a similar-sized hull designed around the massive bow-mounted AN/SQS-26 sonar, with increased endurance and reduced crew size. Anti-submarine armament was to consist of ASROC anti submarine missiles together with the DASH drone helicopter, while defensive armament was to be the RIM-46 Sea Mauler short range anti-aircraft missile backed up by a single 5-inch gun.[3]

The design soon ran into problems, with the US Navy deciding to switch to conventional 1,200 psi (8,300 kPa) boilers, requiring a redesign, with the ships becoming longer and heavier in order to accommodate the less compact power plants. In 1965, Sea Mauler was cancelled, leaving the ships to complete without any surface-to-air missile system.[4][2]

Ten ships were authorized in Fiscal Year 1964, sixteen in 1965 and ten each for FYs 1966, 67 and 68; six were canceled in 1968 and four more in 1969. While the FY64 and FY65 ships were ordered from four different shipyards, later ships (DE-1078 onwards) were all ordered from Avondale Shipyards in order to cut costs.[4] These ships were built on a production line, with prefabricated modules being assembled upside down, welded together and then rotated into an upright position.[5] They were originally commissioned as destroyer escorts (DEs) 1052–1097 in 1969–1974,[2] but were redesignated as frigates (FF) on 30 June 1975.[6]

The Knox class had been criticized for deck wetness and there were a number of instances of damage to the forward weapons mounts in heavy seas. In 1979, the class began to receive "hurricane bows" beginning with USS Bagley (FF-1069). The modification heightened the bow section, adding bulwarks and spray strakes to prevent burrowing into on-coming seas and better protect the forecastle armament.[7]

The Knox class was the Navy's last destroyer-type design with a steam turbine powerplant.

Due to their unequal comparison to destroyers then in service (larger size with lower speed and a only single screw and 5 inch gun), they became known to a generation of destroyermen as "McNamara's Folly."[8]

These ships were retired from the US Navy at the end of the Cold War due to their relatively high running costs, a declining defense budget, and the need for ships with a more advanced antisubmarine capability. None of the ships served more than 23 years in the US Navy, and by 1994 all of the class had been retired, although some remain in service with foreign nations such as Egypt, Taiwan, Thailand, and Mexico.


The Knox class are 438 feet (133.5 m) long overall and 415 feet (126.5 m) at the waterline, with a beam of 46 feet 9 inches (14.2 m) and a draft of 24 feet 9 inches (7.5 m). At 4,200 metric tons (4,130 tons), with a length of 438 feet (133.5 metres) and a beam of 47 feet (14.3 m). The steam plant for these ships consists of two Combustion Engineering or Babcock & Wilcox "D" type boilers, each equipped with a high-pressure (supercharger) forced draught air supply system, with a plant working pressure of 1,200 pounds per square inch (8,300 kPa) and 1,000 °F (538 °C) superheat and rated at 35,000 shaft horsepower (26,000 kW) driving a single screw. This gives them a speed of 27 knots (50 km/h).[9][10]

These ships were designed primarily as antisubmarine warfare platforms.[2] As built, their main anti-submarine sensor was the large bow-mounted AN/SQS-26CX low-frequency scanning sonar, operating as an active sonar at a frequency of about 3.5 kHz and passively at 1.5–4 kHz. The active modes of operation included direct path, to a range of about 20,000 yards (18,000 m), bottom bounce, and convergence zone, which could give ranges of up to about 70,000 yards (64,000 m), well outside the capability of ASROC, and requiring the use of a helicopter to exploit.[2][11][12] Twenty-five ships of the class (DE-1052, 1056, 1063–1071 and 1078–1097) were refitted with the AN/SQS-35(V) Independent Variable Depth Sonar, an active sonar operating at about 13 kHz.[2][9][10] The IVDS' sonar transducers were packaged within a 2-ton fiberglass-enclosed "fish" containing the sonar array and a gyro-compass/sensor package launched by the massive 13V Hoist from a stern compartment, located just beneath the main deck, to depths of up to 600 feet (180 m). The IVDS could take advantage of water layer temperature conditions in close-range (less than 20,000 yards (18,290 m)) submarine detection, tracking and fire-control. The AN/SQS-35 "fish" was later modified to tow an AN/SQR-18A TACTASS passive towed array sonar.[13][14]

As built, they were equipped with one 5 in (127 mm) 54 caliber Mark 42 gun forward, an eight-round ASROC launcher (with 16 missiles carried) abaft the gun and forward of the bridge, with four fixed 12.75 in (324 mm) Mark 32 anti-submarine torpedo tubes. A helicopter deck and hangar for operating the DASH drone helicopter was fitted aft.[5][2] The helicopter facilities were expanded in the 1970s to accommodate the larger, manned, Kaman SH-2D/F Seasprite LAMPS 1 helicopter.[15] While as built, anti-aircraft capabilities were limited to the 5-inch gun, it was planned to refit the ships with a short range surface to air missile system to replace the cancelled Sea Mauler. 31 ships (DE-1052–1069 and 1071–1083) were fitted with an eight-round Basic Point Defence Missile System launcher for RIM-7 Sea Sparrow missiles, while DE-1070 was fitted with an improved NATO Sea Sparrow launcher. It was planned to equip the other 14 ships with Sea Chaparral, based on the Sidewinder air-to-air missile, but this plan was abandoned.[16] All ships were refitted with a 20 millimetre Phalanx CIWS aft during the 1980s, replacing the Sea Sparrow launcher where fitted.[13] Surface warfare weaponry was at first similarly limited to the gun, with several ships receiving an interim upgrade allowing Standard ARM anti-radar missiles to be fired from the ships' ASROC launcher in the 1970s.[16] Later, all ships were modified to launch Harpoon anti-ship missiles from the ASROC launcher, which could carry two Harpoons, with two more carried in the ships' ASROC magazine.[13]

Baleares class

Five modified ships were built in Spain for the Spanish Navy as the Baleares-class frigates.

Chi Yang class

In the 1990s, the US agreed to transfer 8 Knox-class frigates to the Republic of China Navy (ROCN). The ROCN, anticipating future difficulties in maintaining the steam plants on these ships, originally contemplated an ambitious plan to replace these plants with diesel engines. However, due to budget considerations and the acquisition of newer ships, this plan is now believed to have been shelved. These frigates were renamed the Chi Yang class and assigned to the ROCN 168 Patrol Squadron.[17]

By 2005, the ROCN had removed several systems from the retired Gearing class upgraded World War II-vintage destroyers and transferred them to seven of the Chi Yang class. These systems include SM-1MR Standard missile in box launchers, H-930 modular combat system, and DA-08 air/surface search radar. Each Chi Yang-class frigate has 10 SM-1 missiles installed in two forward twin box launchers on top of the helicopter hangar, and two triple box launchers installed between the stack and the hangar, pointing to port and starboard.[18] Chi Yang (FFG-932) did not receive the upgrade.

The anti-submarine capability of the Chi Yang class is provided by its SQS-26 bow-mounted sonar, SQS-35(v) VDS, SQR-18(v)1 passive TAS, MD500 ASW helicopter, Mk-16 8-cell Harpoon/ASROC box launcher, and 4 x Mk46 324 mm torpedoes. While on ASW patrol, the frigate will carry 2 x Harpoon SSMs and 6 x ASROCs in its Mk-16 box launcher.[19]

There are some speculations that these ships will probably be upgraded with Hsiung Feng III missiles.[20]


Ship Name Hull No. Builder Commission–
Fate Link
KnoxFF-1052Todd, Seattle1969–1992Sunk as target
RoarkFF-1053Todd, Seattle1969–1991Scrapped
GrayFF-1054Todd, Seattle1970–1991Scrapped
HepburnFF-1055Todd, San Pedro1969–1991Sunk as target
ConnoleFF-1056Avondale1969–1992To Greece, renamed Ipirus (F-456) Sunk as target
RathburneFF-1057Lockheed1970–1992Sunk as target
MeyerkordFF-1058Todd, San Pedro1969–1991Scrapped
W. S. SimsFF-1059Avondale1970–1991Grant aid to Turkey as spare parts hulk
LangFF-1060Todd, San Pedro1970–1991Scrapped
WhippleFF-1062Todd, Seattle1970–1992To Mexico, renamed Almirante Francisco Javier Mina (F-214)
ReasonerFF-1063Lockheed1971–1993To Turkey, renamed Kocatepe (F-252)
LockwoodFF-1064Todd, Seattle1970–1993Scrapped
SteinFF-1065Lockheed1972–1992To Mexico, renamed Ignacio Allende (F-211)
Marvin ShieldsFF-1066Todd, Seattle1971–1992To Mexico, renamed Mariano Abasolo (F-212)
Francis HammondFF-1067Todd, San Pedro1971–1992Scrapped
VreelandFF-1068Avondale1970–1992To Greece, renamed Makedonia (F-458) Decommissioned
DownesFF-1070Todd, Seattle1971–1992Sunk as target
BadgerFF-1071Todd, San Pedro1970–1991Sunk as target
Robert E. PearyFF-1073Lockheed1972–1992To Taiwan, renamed Chih Yang (FF-932) Decommissioned
Harold E. HoltFF-1074Todd, San Pedro1971–1992Sunk as target
TrippeFF-1075Avondale1970–1992To Greece, renamed Thraki (F-457) sunk as target
FanningFF-1076Todd, San Pedro1971–1993To Turkey, renamed Adatepe (F-251)
OuelletFF-1077Avondale1970–1993To Thailand, renamed HTMS Phutthaloetla Naphalai
Joseph HewesFF-1078Avondale1971–1994To Taiwan, renamed Lan Yang (FF-935)
BowenFF-1079Avondale1971–1994To Turkey, renamed Akdeniz (F-257)
PaulFF-1080Avondale1971–1992To Turkey as spare parts hulk
AylwinFF-1081Avondale1971–1992To Taiwan, renamed Ning Yang (FF-938)
Elmer MontgomeryFF-1082Avondale1971–1993To Turkey as spare parts hulk
CookFF-1083Avondale1971–1992To Taiwan, renamed Hae Yang (FF-936) Decommissioned
McCandlessFF-1084Avondale1972–1994To Turkey, renamed Trakya (F-257)
Donald B. BearyFF-1085Avondale1972–1994To Turkey, renamed Karadeniz (F-255)
BrewtonFF-1086Avondale1972–1992To Taiwan, renamed Fong Yang (FF-933)
KirkFF-1087Avondale1972–1993To Taiwan, renamed Fen Yang (FF-934)
BarbeyFF-1088Avondale1972–1992To Taiwan, renamed Hwai Yang (FF-937)
Jesse L. BrownFF-1089Avondale1973–1994To Egypt, renamed Dumyat (F961)
AinsworthFF-1090Avondale1973–1994To Turkey, renamed Ege (F-256)
MillerFF-1091Avondale1973–1991To Turkey as spare parts hulk
Thomas C. HartFF-1092Avondale1973–1993To Turkey, renamed Zafer (F-253)
CapodannoFF-1093Avondale1973–1993To Turkey, renamed Muavenet (F-250)
PharrisFF-1094Avondale1974–1992To Mexico, renamed ARM Guadalupe Victoria (F-213)
TruettFF-1095Avondale1974–1994To Thailand, renamed HTMS Phutthayotfa Chulalok
ValdezFF-1096Avondale1974–1991To Taiwan, renamed Ki Yang (FF-939)
MoinesterFF-1097Avondale1974–1994To Egypt, renamed Rasheed (F.962)
UnnamedDE-1098 through DE-1100[21]N/A N/ACancelled 24 February 1969[1]
(DE-1101 was to be an experimental ship)
DE-1102 through DE-1107

See also



  1. Bauer and Roberts 1991, pp. 244
  2. Gardiner and Chumbley 1995, pp. 598–599.
  3. Friedman 1982, pp. 358–360.
  4. Friedman 1982, p. 360.
  5. Blackman 1971, p. 481.
  6. Polmar 1981, p. 113.
  7. Friedman, Norman (2004). US Destroyers: An Illustrated Design History (Revised Edition). Annapolis: Naval Institute Press. p. 360. ISBN 978-1-55750-442-5.
  8. "Knox class". Archived from the original on 1 June 2009. Retrieved 3 November 2009.
  9. Polmar 1981, p. 121.
  10. Prézelin and Baker 1990, p.807.
  11. Friedman 1997, pp. 629–630.
  12. Gardiner and Chesneau 1995, p. 553.
  13. Prézelin and Baker 1990, p.808.
  14. Moore 1985, p. 718.
  15. Moore 1985, p. 717.
  16. Friedman 1982, p. 361.
  17. "Chi Yang-class [Knox] Frigate". 11 July 2011. Retrieved 7 October 2014.
  18. "070402-P-Taiwan". Archived from the original on 27 September 2007. Retrieved 3 July 2007.
  19. Emerald Designs. Destroyer Archived 8 June 2007 at the Wayback Machine
  20. "Taiwan to expand missile deployment to counter China's navy". 16 February 2013. Retrieved 7 October 2014.
  21. These ships are noted with the original 'DE' hull code as they were cancelled prior to the 1975 ship reclassification plan.


  • Blackman, Raymond V. B. (ed.) Jane's Fighting Ships 1971–72. London: Sampson Low, Marston & Co., Ltd., 1971. ISBN 0-354-00096-9.
  • Friedman, Norman. The Naval Institute Guide to World Naval Weapon Systems 1997–1998. Annapolis, Maryland, USA: Naval Institute Press, 1997. ISBN 1-55750-268-4.
  • Friedman, Norman. U.S. Destroyers: An Illustrated Design History. Annapolis, Maryland, USA: Naval Institute Press, 1982. ISBN 0-87021-733-X.
  • Gardiner, Robert and Stephen Chumbley (eds.) Conway's All The World's Fighting Ships 1947–1995. Annapolis, Maryland, USA: Naval Institute Press, 1995. ISBN 1-55750-132-7.
  • Moore, John. (ed.) Jane's Fighting Ships 1985–86. London: Jane's Yearbooks, 1985. ISBN 0-7106-0814-4.
  • Polmar, Norman. The Ships and Aircraft of the U.S. Fleet. Twelfth Edition. London: Arms and Armour Press, 1981. ISBN 0-85368-397-2.
  • Prézelin, Bernard and A.D. Baker III (editors). The Naval Institute Guide to Combat Fleets of the World 1990/91:Their Ships, Aircraft and Armament. Annapolis, Maryland, USA: Naval Institute Press, 1990. ISBN 0-87021-250-8.
  • Bauer, K. Jack; Roberts, Stephen S. (1991). Register of Ships of the U.S. Navy, 1775-1990: Major Combatants. Westport, Connecticut: Greenwood Press. ISBN 0-313-26202-0.
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