Bedeviled with cost overruns, the Navy's shipbuilding program is in danger of sinking under its own weight. Navy leaders have struggled to upgrade an aging fleet of warships with next-generation aircraft carriers, destroyers, amphibious assault ships and submarines that cost billions more than the vessels they replace. Seven new ships are budgeted for this year, barely a third of the number built annually during the peak Reagan-era defense buildup. Fifteen will be decommissioned, including the San Diego-based Ogden, Trenton and Dolphin. The result is a fleet of 276, the lowest total in nine decades. “The number of ships we're producing...