Michael Melia, Associated Press

GROTON, Conn. (AP) — The U.S. Navy's primary contractor for submarines is hiring hundreds of employees and putting up new buildings as it doubles production of fast-attack submarines and ramps up design work for a new generation of ballistic missile vessels, company officials said Wednesday.

The hiring is part of a mini boom at Electric Boat, a Groton-based division of General Dynamics Corp. where thousands of workers design and assemble nuclear submarines on a shipyard ringed with barbed wire along the Thames River.

Over the last year, the company has added 270 employees in Groton and an additional 260 at its Quonset Point, R.I., manufacturing plant, spokesman Robert Hamilton said. Company officials expect hiring to remain in the low hundreds over each of the next few years. A total of 10,790 people are employed at the two sites.

"We're trying to support whatever the Navy wants to do," Hamilton told reporters during a tour of the facility.

In April, the Navy released money for Electric Boat to begin producing two Virginia-class attack submarines a year, a move aimed at slowing a post-Cold War decline in the size of the U.S. submarine force. It marked the first time since 1991 that the company received funds for two ships in a year.

The company is putting up new, cavernous buildings at Quonset Point for the ramped-up submarine construction. It also has begun moving workers to the former Pfizer headquarters in New London, a building that it purchased last year with assistance from the state of Connecticut because it was running out of room at the Groton campus.

Another factor in the hiring is the design work for the submarines to replace the aging Ohio-class submarines, according to Daniel Panosky, the company's director of naval architecture.

The Ohio-class ships are much larger than the attack submarines and carry ballistic missiles as part of the U.S. nuclear weapons arsenal. The replacement submarines, which are to be built over 10 years beginning in 2019, have been described by Electric Boat president John Casey as the company's "real future."

The Virginia-class attack submarines are designed to fill a number of roles, including sinking ships, launching cruise missiles, gathering intelligence and delivering Navy SEALs to trouble spots via a minisub carried piggyback-style. Electric Boat builds them jointly with a Huntington Ingalls Industries shipyard in Newport News, Va., at a cost of about $2.6 billion each.

Since the first Virginia-class submarine was delivered in 2004, the company has reduced the number of man hours required to build them from 14 million to roughly 10 million — a streamlining that it attributes to design innovations and lessons learned from constructing earlier hulls.

With 11 more of the ships under contract, company officials say they are working to reduce the amount of maintenance costs at the Navy's request. While the Virginia-class ships currently have to be in dry dock for major work four times over their 33-year lifespan, engineers are working to reduce that to three and give the Navy more deployments, according to John Pavlos, an engineer involved in refining the Virginia-class design.

In one example, the company plans to introduce a thicker paint for the submarine hulls that will not have to be reapplied as often.