Which country mass-produced speedboats packed with explosives as a weapon during WW2?

The Shinyo ("Sea Quake") were Japanese suicide boats, driven by one man, to speeds of around 30 kn (56 km/h; 35 mph). Around 6,200 Shinyo were produced for the Imperial Japanese Navy and stored on the coast of Japan for the ultimate defense against the invasion of the Home Islands. Only a small number of them were used in action in the Phillipines and Okinawa, sinking some gunboats and auxiliary ships.