Run Silent, Run Deep

Tom Clancy would love it: an ungainly ship with a state-of-the-art silent propulsion system that is virtually undetectable, even at speeds up to 115 m.p.h. Last month Japan launched the prototype. Christened the YAMATO (also the name of the imperial navy’s World War II flagship), the vessel is the first in the world propelled by superconducting magnets that generate a ! powerful jet of water. Such a stealth design so far exists only in the imaginations of Western engineers. The Yamato, of course, is not a warship. But if Japan wanted to build a war machine, it has just the technology for a formidable fleet.