Tapi-class corvette

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Class overview
Name: Tapi class
Builders: American Shipbuilding Co / Norfolk Shipbuilding & Drydock Co, both USA
Operators:  Royal Thai Navy
Built: 1970-1974
In commission: 1971-present
Completed: 2
Active: 2
General characteristics Following 1980s refit and rearmament[1]
Type: Corvette
  • 885 long tons (899 t) standard
  • 1,172 long tons (1,191 t) full load
Length: 275 ft (83.8 m)
Beam: 33 ft (10.1 m)
Draft: 14 ft 1 in (4.3 m) (sonar dome)
  • 2× Fairbanks-Morse 38TD8-1/8-9 diesel engines, 2 shafts
  • 5,250 hp (3,910 kW)
Speed: 20 kn (23 mph; 37 km/h)
Range: 2,400 nmi (2,800 mi; 4,400 km) at 18 knots (21 mph; 33 km/h)
Complement: 15 officers, 120 enlisted
Sensors and
processing systems:
  • Radar:
  • Signaal LW04 Air/surface search
  • Raytheon SPS-53E surface search
  • Signaal WM-22-61 fire control
  • Sonar:
  • Atlas Elektronik DSQS-21C hull-mounted, medium frequency active search/attack

Tapi-class corvettes are a class of two corvettes that were built for the Royal Thai Navy in the early 1970s. Both ships remain in service.

Design and construction[edit]

In 1969, Thailand ordered from the United States a single small PF 103-class frigate, of which four examples, the Bayandor class, had been built for Iran in the 1960s, with a second example being ordered in 1971. For procurement purposes, they were allocated the US Navy hull numbers PF 107 and PF 108.[2]

As built, single 3 inch/50 calibre Mk 34 automatic anti-aircraft guns were mounted fore and aft,[2] each capable of firing 6.8 kg (15 lb) shells to a range of 13,400 metres (14,600 yd) at a rate of 45 rounds per minute,[3] backed up by a twin Bofors 40mm/L60 mount. Two triple Mark 32 torpedo tubes for anti-submarine torpedoes and a Hedgehog anti-submarine mortar comprised the ships' anti-submarine armament.[2] AN/SPS-6 air-search radar and SQS-17 sonar comprised the ships' sensor suite.[2]

Operational history[edit]

The first ship, Tapi, was commissioned on 19 November 1971, with the second ship, Khirirat, following on 10 August 1974.[1] Both ships were modernised during the 1980s, with the US 3-inch guns being replaced by a rapid fire OTO Melara 76 mm gun forward, and a Bofors 40mm/70 gun aft, with two single 20 mm cannon replaced the existing twin Bofors mount. The obsolete Hedgehog was removed, and the ships were fitted with new radar and sonar systems.[2][1]

As of 2002, they were used for patrolling Thailand's Exclusive economic zone.[1]


Name Builder Laid Down[4] Launched[4] Commissioned[4]
(later 431)
Tapi American SB Co, Toledo, Ohio 1 April 1970 17 October 1970 1 November 1971
(later 432)
Khirirat Norfolk SB 18 February 1972 2 June 1973 10 August 1974



  1. ^ a b c d Saunders 2002, p. 708.
  2. ^ a b c d e Gardiner and Chumbley 1995, p. 462.
  3. ^ Friedman 1997, p. 463.
  4. ^ a b c Baker 1998, pp. 870–871.


  • Baker, A.D. (1998). The Naval Institute Guide to Combat Fleets of the World 1998–1999. Annapolis, Maryland, USA: Naval Institute Press. ISBN 1-55750-111-4. 
  • Friedman, Norman (1997). The Naval Institute Guide to World Naval Weapon Systems 1997–1998. Annapolis, Maryland, USA: Naval Institute Press. ISBN 1-55750-268-4. 
  • Gardiner, Robert; Chumbley, Stephen (1995). Conway's All The World's Fighting Ships 1947–1995. Annapolis, Maryland, USA: Naval Institute Press. ISBN 1-55750-132-7. 
  • Saunders, Stephen (2002). Jane's Fighting Ships 2002–2003. Coulsdon, UK: Jane's Information Group. ISBN 0710624328.