Hull sections of the future U.S. Navy submarine Washington have been joined into a single watertight unit by Newport News Shipbuilding.

The vessel is the seventh Virginia-class submarine by Newport News Shipbuilding and the 14th for the Navy.

Huntington Ingalls Industries, parent company of the shipbuilder, said construction of the submarine Washington (SSN 787) began in 2011 under a teaming agreement with General Dynamics Electric Boat.

The joining of the hull sections into a single watertight unit -- termed "pressure hull complete" -- is an indication that the vessel is 83 percent complete, the company said.

"Pressure hull complete is an exciting step toward the boat's completion because it's the point when the submarine really starts to take its final shape and is the last major construction milestone before christening and delivery next year," said Jim Hughes, Newport News' vice president of submarines and fleet support. "As with all of our Virginia-class submarines, Washington represents a true team effort that involves our partners at General Dynamics Electric Boat, the Navy, our suppliers and the Washington crew."