fighting ships of the world



RATANAKOSINDRA armoured gunboats (1925-1930)

Ratanakosindra 1935

Ratanakosindra 1960

Name No Builder Laid down Launched Comp Fate
รัตนโกสินทร์ <Ratanakosindra>   Armstrong, Elswick, UK 9/1924 21/4/1925 8/1925 stricken 10/1967
สุโขทัย <Sukothai>   Vickers-Armstrong, Barrow, UK 12/1928 19/11/1929 12/1930 stricken 1971


Displacement standard, t


Displacement full, t


Length, m

48.8 pp 53.0 oa

Breadth, m


Draught, m


No of shafts



VTE, 2 Yarrow boilers

Power, h. p.


Max speed, kts


Fuel, t

oil 96

Endurance, nm(kts)


Armour, mm belt: 57 - 32, deck: (25 - 13) + 25, turrets: 38, barbettes: 38, CT: 120


2 x 1 - 152/50 EOC TT, 4 x 1 - 76/40 EOC N



Ship project history: Program of strengthening of Siamese Navy accepted in 1914 provided the order in the Great Britain of two original armoured gunboats (actually low-freeboard monitors). Total displacement should make 1070t, armament consist from 4 152mm/50 and 4 76mm/40 Armstrong guns, machinery include VTEs and cylindrical coal-firing boilers. Lead Ratanakosindra was laid down in 1914 by Armstrong in Elswick, but in connection with beginning of the First World War building was suspended, and partially assembled hull was broken up to clear a slipway. Ship was re-ordered in 1924 under changed project. Number of main guns was decreased to two, cylindrical boilers were replaced by Yarrow oil-firing water-tube boilers, also VTE of a new construction were installed, but with the same power. The given measures have allowed to increase a fuel stowage (normal from 15 to 85t, and full from 50 to 96t) and thus to decrease a draught a little.
Ratanakosindra was built at High Walker, 10/8/1925 she was commissioned and 31/8/1925 departured from Britain to Siam, but those day she received damages as result of collision and returned to builder for repair; she ultimately left Great Britain 29/10/1925. Sukothai ("City of angels": a poetical name of Bangkok) was ordered in 1928 to already Vickers-Armstrong, building was conducted in Barrow.
Ships differed by rather unusual hull structure combining low free board typical for monitors with raised forecastle, improving seaworthiness. On trials Ratanakosindra shown 12.892kts. Outwardly Sukothai differed by increased bridge and transferred on 3m aftward funnel.

Ship protection: Main belt, 2m in height, had 57mm thickness amidships, decreasing to 32mm at ship ends. There were two armoured decks: upper had 25mm thickness over machinery, 19mm over aft end and 13mm over fore end, lower deck was uniform with 25mm thickness. Turrets and barbettes had 38mm protection from all directions, CT had 120mm armour.

Modernizations: mid-1930s, both: + 2 x 1 - 40/39 2pdr QF Mk II

mid-1940s, both: + 2 x 1 - 20/65 Breda 1939

Naval service: Both ships served more than 40 years.

Ratanakosindra 1926

Ratanakosindra 1950

Ivan Gogin, 2011-15