In 1989 Burma bought 3 Romeo class submarines from China (second hand). Ayutthaya only have 2 Knox Class frigates and the very old ASW corvettes ship. The navy plan the urgent projects for protection this submarines by
1 Buy 2 modern ASW corvettes have helicopter flight deck for use with SH-2F Seasprite ASW helicopters.
2 Upgrade the old corvettes with the new weapons.
3 build the small craft by local shipyard with the Anti-submarine weapons. So the modern fast attack craft project was born again in the other mission by reduce some specification and install ASW weapons.
Ayutthaya Araya Class 1991 : Anti-submarine warfare(ASW) Fast Attack Craft or Anti-submarine warfare Corvette.
General specifications:
length: 61.8 m
beam: 9.2 m
draft: 3.2 m
displacement (max): 550 t
speed: 25 kts
range: 2,950 nm @ 14 kts
complement: 52
propulsion: 2xdiesel engines MTU 20 V 538 TB92 6,600 kW
2xshafts with controllable pitch propellers
Sensors:
1xThales ZW06 a surface search and navigation radar
1xThales WM28 mod.41 fire control radar
1xKelvin-Hughes 1006 navigational radar
1xESM Elettronica ELT 211
1xAtlas DSQS-21C Sonar
Communication systems:
UHF antennas
Link11 (1996)
Armament:
1xOto Melara 76/62 mm compact gun
1xBreda/Bofors Type 564 40/70 gun (old part)
2xM2HB machine guns
2xMk32 3-tube torpedo launchers for Mk46 torpedoes
1xDepth Charge Rack Mk3 (old part)
1xRHIB Boat
1x1.5tons Crane