One of the Royal Thai Navy’s two Ratanakosin-class corvettes, the HTMS Sukhothai, sank in extreme weather conditions early Monday morning, Thai media reported. Search and rescue operations are underway, the initial cause was believed to be due to high waves. Strong winds tilted the 76.8 m long corvette, allowing sea water to enter an exhaust pipe and subsequently shut down the ship’s electrical system, a Thai navy statement said.
HTMS Sukhothai with a displacement of 960 tons was built in the US and entered service with the Royal Thai Navy in 1987. Together with the HTMS Ratanakosin, the Class was used as flagship for for squadrons of fast attack craft. A third ship was planned to be built in Thailand, but was canceled before construction could begin.
HTMS Sukhothai and her sister were built on the design of Saudi Arabia’s Badr class, with a full load displacement of 960 t. The corvette is 76.82 m long, the beam is 9.55 m, and the draft is 2.44 m. The class is powered by 2 x MTU 20V1163 TB83 diesel engines each driving one shaft rated at 16,000 bhp. This gives the vessels a maximum speed of 26 knots and a range of 3,000 nautical miles at 16 knots. The ships have a complement of 15 officers and 72 enlisted.
HTMS Sukhothai is equipped with one Decca 1226 and one HSA ZW-06 surface search radar, one HSA DA-05 air/surface search radar, one HSA WM-25 fire control radar, one HSA LIROD-8 optical fire control system, and one STN Atlas DSQS-21C hull-mounted sonar.
The corvettes are armed with two quad launchers for eight RGM-84 Harpoon surface-to-surface missiles (SSM) and one octuple Albatros launcher for 24 Selenia Aspide surface-to-air missiles (SAM). Furthermore, the vessels are armed with one Otobreda 76 mm gun, two Bofors 40 mm guns in a twin Otobreda mount and two 20 mm Oerlikon GAM-B01 cannon. The Ratanakosin class is also equipped with two Mark 32 triple torpedo tubes for Sting Ray torpedoes.
Basically the Ratanakosin class was quite old, and the Thai crew faced a difficult situation on such an old ship. The severe weather in the Gulf of Thailand, about 20 miles (32 kilometers) from Bang Saphan District, continued into late Monday morning, hampering search efforts for the missing crew, authorities said.