BATH (AP) – Bath Iron Works, which is preparing for a lean stretch even if the next-generation destroyer proceeds on schedule, announced it is suspending the “vast majority” of third-shift operations.

The company said the move would occur June 6 and was being taken to reduce the hours and costs of building destroyers for the Navy.

“I do not take this action lightly,” BIW President Dugan Shipway wrote in a Tuesday bulletin to employees. The third shift runs from 11:30 p.m. to 7 a.m. and has 267 people in it. The work will be consolidated to first and second shifts.

A union official speculated that the action could lead to layoffs in support personnel, of which there are about 30 working the late nights.

A shipyard official declined to discuss specifics.

Mike Keenan, president of the 3,850-member Machinists Union Local S-6, said the company’s decision reneges on a contract negotiated a year ago.

Last May, the union and BIW negotiated a 7.5-hour shift for the third shift, instead of the previous 8.5-hour shift, Keenan said. The contract also included a shift premium for late-night workers, he said, up to $1.25 an hour.

“It was an attractive incentive to get folks onto the off-shift. It also sold the contract to many of our members working the third shift,” he said. “The company sadly has a right to violate the labor agreement. There’s a penalty, but they have a right.”

The elimination of the third shift comes as Bath Iron Works is fighting to continue to make destroyers for the Navy.

Under a best-case scenario, Bath Iron Works is looking at a workload gap anticipated as the shipyard transitions from the current Arleigh Burke destroyer program to the next generation DD(X) destroyer four years down the road.

But delays in the program could exacerbate problems, and the Navy’s proposal for a winner-take-all proposal could drive either Bath Iron Works or its chief competitor, Mississippi’s Northrop Grumman Ingalls shipyard, out of business.

Keenan said about 235 union members work on the third shift; the remaining 30 people would be support and management personnel. He said elimination of the shift would likely result in layoffs of those support workers, who run cranes, drive trucks, run equipment depots and perform other functions.

Asked about the possibility of layoffs, shipyard spokesman Dirk Lesko told the Portland Press Herald that “this will result in efficiencies that relate to support functions.” He added that the efficiencies went beyond personnel, to costs such as the energy expenses of running the building for the shift and other factors.

In the employee bulletin, Shipway wrote, “This decision was reached after careful review and analysis of all costs and cost efficiencies associated with performing work on third shift, including support and supervision costs, and considers lower construction throughput requirements associated with current U.S. Navy shipbuilding.”

Bath Iron Works has about 6,200 employees and is owned by General Dynamics, which is headquartered in Falls Church, Va.