G - 5 - class motor torpedo boat The G - 5 was a Soviet motor torpedo boat built before and during World War II . Approximately 300 were built , of which 73 were lost during the war . Four were exported to the Spanish Republican Navy during the Spanish Civil War and others were transferred to North Korea after the war . Three were captured by the Finns , but only two were used before all three had to be returned to the Soviets after the Moscow Armistice in 1944 . Design and development . The G - 5 class was an improved and enlarged version of the s which were derived from a design by Andrei Tupolev , the noted aircraft designer . It was intended to use Soviet - built engines and carry larger torpedoes than its predecessor . A prototype was designed and built by TsAGI ( or " Tsentralniy Aerogidrodinamicheskiy Institut " , the Central Aerohydrodynamic Institute ) in 1932 – 33 . As its intended engines were not yet available two Isotta - Fraschini engines were imported from Italy . Unarmed , and with a partial fuel load , it achieved a maximum speed of during its trials in the Black Sea during 1933 and the decision was made to place it into production . The G - 5 was a single - step , hydroplaning design with a whaleback upper hull . It was mainly built from duralumin which saved a significant amount of weight , but greatly complicated its use in service because of duralumin ' s susceptibility to galvanic corrosion in salt water . One captured Soviet torpedo boat commander said that G - 5s could only be kept in the water for 5 – 7 days during the summer and 10 – 15 days during the winter before it had to be removed from the water and treated with anti - corrosion measures . The hull was divided into three compartments by two transverse bulkheads . The superstructure was very small to reduce top - heaviness , and crewmembers could not stand up inside it . The G - 5 was designed to use a version of the Mikulin AM - 34 aircraft engine adapted for maritime use as the GAM - 34 . The two engines were fitted in the forward compartment of the hull . Each engine had its own transmission and drove a bronze propeller in diameter . The initial version of the GAM - 34 was less powerful than planned at only and the initial Series 7 boats could only reach . However the minimum speed was which caused a great deal of trouble when trying to moor and when maneuvering in close proximity . The two torpedoes were carried in troughs set into the rear deck in a manner derived from that used by the British WW I - era coastal motor boat s captured by the Soviets during Russian Civil War . The torpedoes were shoved out the back of the trough by an arbor with a bell - shaped head that was activated by an explosive charge , but the torpedo motor was not activated until a wire trailing from the boat snapped , giving the boat time to turn away from the target . This launching system was very light , but it required additional training to properly aim the torpedo and prior coordination when making massed torpedo attacks to prevent the boats from ramming each other or the torpedoes . The gun armament initially consisted of a single machine gun , but this was upgraded to a DShK machine gun in later models . Some later boats carried two DShKs although the mounts varied ; some were placed in a tub in the forecastle , but others carried theirs in a rotating turret behind the superstructure , above the torpedoes . Some boats carried ROFS - 82 or ROFS - 132 rocket launchers in fixed mounts above and behind the wheelhouse . Production . Approximately 300 G - 5s were built . 152 of the Series 7 , 8 and 9 boats were built between 1934 and 1936 . 20 Series 10 boats were built in 1937 , another 76 in 1938 – 39 and five in 1939 – 40 . 39 Series 11 boats were built beginning in 1941 and production may have continued during the war . Service history . On 22 June 1941 , the day that the Germans invaded the Soviet Union , 254 G - 5s were in service . The Baltic Fleet had 60 , the Black Sea Fleet had 92 , the Pacific Fleet had 135 and the Caspian Flotilla had six . During the war 73 were lost in action and 31 were scrapped after becoming unserviceable . By the end of the war in 1945 24 were in service with the Baltic Fleet , 134 were with the Pacific Fleet and six were still with the Caspian Flotilla . On 18 November 1942 the Finnish motor torpedo boat " Syöksy " , the captured G - 5 boats " Vinha " and " Vihuri " , as well as a minelaying KM - boat , attacked Soviet ships in the harbour of Lavansaari . " Syöksy " sank the , although she was later raised and put back into service . Exports . Four boats were transferred to the Spanish Republican Navy during the Spanish Civil War , two continue in service after the war in the Spanish navy until 1946 . A number were transferred to North Korea after the end of the war .