> But you don't need that if the vessel is electric-powered, like a nuclear-powered sub Yep. > I believe some modern warships use a traditional motor to drive

> But you don't need that if the vessel is electric-powered, like a nuclear-powered sub Yep. > I believe some modern warships use a traditional motor to drive a generator, which drives an electric motor for propulsion Sure, like a diesel-electric locomotive. It turns out in some situations it's better to eat the conversion loss from electric generation rather than using a direct mechanical linkage, because then you can use flexible cables and electrical control systems rather than a bunch of mechanical folderol