A secret chapter in American naval research could soon reach an ignoble close when a rusty barge and its once-classified contents leave Suisun Bay for the scrap heap. Slipping through the sea like a black mirage on catamaran legs, the 164-foot Sea Shadow looks like something Darth Vader might fly. It is the world's only ship built to be invisible, assembled secretly in Redwood City in 1985 by the U.S. Navy and contractor Lockheed Martin at an estimated cost of $50 million. Sea Shadow's purpose was to test radar-cloaking technology and other naval engineering innovations. Many of its breakthroughs can...