Siam ordered the building of torpedo motor boats by Thornycroft, England according to the Dutch magazine Marineblad dated 1936 no. 3

An item referred to the magazine Schiffbau 15 March 1935 reporting that Siam let Thornycroft built torpedo motor boats for her navy with as dimensions 16,8 x 3,35 x 0,6 (at full speed)-1,14 metres with a displacement of 14 ton. At a trial on the Thames was in February 1936 a maximum speed of 42,4 miles achieved. The 2-475 hp 12 cylinder engines each weighing around 1.000 kilo allowed with a speed of 40 knots and a fuel capacity of 1.820 litre a range of 260 nautical miles with a speed of 40 miles.  There was also a 30hp engine available which connected with the port board propellor shaft allowed with a speed of 7 miles a range of 650 nautical miles. The armament consisted of 2-45,7cm torpedo tubes, 2 machine guns and 2-180 kilo depth charges. The range of the radio was just 90 miles.