Ingalls Shipbuilding is to construct a seventh Legend-class National Security Cutter for the U.S. Coast Guard under a new $497 million contract.

Huntington Ingalls Industries, of which the company is a part, announced that work on the new cutter will begin next year. It will be delivered in 2018.

"We have a hot production line with this class of ships, and we continue to get better -- a tangible result demonstrating the value of serial production," said Ingalls NSC Program Manager Jim French. "Each ship is built more effectively and more affordably than the one before it, and this is due to the hard work of our shipbuilders who are implementing efficient build plans and bringing our learning curve down as each ship is delivered."

The first three Legend-class cutters have been delivered to the Coast Guard and three more are currently under construction.

The Hamilton is 81 percent complete and will be delivered later this year. The James is half complete and will be launched this month next year, while the sixth cutter will be launched in the third quarter of next year.

Legend-class cutters are 418 feet long, 54 feet in the beam and have a speed of more than 28 knots. Their range is 12,000 nautical miles. They are replacing Hamilton-class cutters now in service.

They feature an aft launch and recovery area for two rigid hull inflatable boats and a flight deck.