Bath, Maine — The largest destroyer built for the U.S. Navy cuts an imposing figure: massive, with an angular shape, hidden weapons and antennas, and electric-drive propulsion. But underneath the stealthy exterior resides a style of hull that fell out of favor a century ago in part because it can be unstable. The Navy will soon learn how this modern take on the “tumblehome†hull holds up when the first-in-class Zumwalt heads out to sea in December for builder trials in the rough-and-tumble North Atlantic. Amy Lent, of the Maine Maritime Museum, which works closely with the shipyard, said taxpayers...