Bath Iron Works has lifted a 900-ton deckhouse onto the 610-foot hull of the Zumwalt, the largest destroyer to be built at the Maine shipyard. Officials said Thursday that on Dec. 13 and 14 it took four cranes to lift the deckhouse, the heaviest item ever lifted at the shipyard. That was followed by the movement of the entire assembly weighing 13,000 tons back into position for shipbuilders to continue assembly. The stealthy destroyer, the Zumwalt, features a wave-piercing hull, electric drive propulsion, and powerful guns and missiles. It will be christened in 2013 and delivered to the Navy late in the following year.