General Dynamics NASSCO received funds to build an expeditionary sea base, a 784-foot ship similar to the USNS Lewis B. Puller, shown here - Photo courtesy of General Dynamics NASSCO

General Dynamics NASSCO received funds to build an expeditionary sea base, a 784-foot ship similar to the USNS Lewis B. Puller, shown here - Photo courtesy of General Dynamics NASSCO

General Dynamics NASSCO received a $325 million deal to help fund the fifth in a series of U.S. Navy support ships.

The contract modification, announced by the U.S. Navy on Dec. 29, will cover long lead-time materials as well as the design and construction of a 784-foot ship called an expeditionary sea base.

The distinctive-looking expeditionary sea base includes a flight deck that can hold up to four helicopters. The flight deck sits on pillars above a mission deck which might hold small watercraft, but can be reconfigured for other purposes. The support ship, which resembles a tanker in some ways, also includes accommodations for U.S. Marines.

Work will run through May 2019, and about three-quarters of the work will be done in San Diego. Other work will go to subcontractors around the United States.

The Naval Sea Systems Command of Washington, D.C. awarded the deal.

NASSCO runs a shipyard on Port of San Diego property in Barrio Logan. Shares of NASSCO parent General Dynamics trade on the New York Stock Exchange as GD.

The expeditionary sea base will be the fifth ship in a series that began with the expeditionary transport dock (originally called the mobile landing platform).