The G7a(TI) was the standard issue Kriegsmarine torpedo during the early years of World War II. It was a steam-powered design, using a wet heater engine burning decaline, with a typical range of about 7,500 metres (24,600 ft) while running at 40 knots (74 km/h; 46 mph). It was replaced beginning in 1942 by the electrically powered G7e torpedo, which did not leave a trail of bubbles in the water and thus did not reveal the location of the submarine.