The Soviet Sh-4 and stern-launched torpedoes

The Sh-4 launched its torpedoes from stern cradles, then turned away from their course. Formation attacks required precise instructions about where each boat would turn because crews could otherwise endanger neighbouring boats with their own weapons. Its whaleback hull and enclosed conning position reflected an ambition to operate at high speed in rough northern waters, although boats also went to the Black Sea. The 1928 version displaced 10.9 tons standard and used two American Wright Typhoon petrol engines for a stated 44 knots, below the earlier 49-knot figure. Armament comprised two 18-inch torpedoes and one .3-inch machine gun, with a crew of six. Limited endurance, poor maintenance, and the demands of its aluminium-copper structure left the type largely worn out by the late 1930s.