Groton ― Electric Boat and a labor union that represents thousands of shipyard workers have tentatively agreed to a new five-year contract.

In a joint statement released Friday night, the submarine builder and the Metal Trades Council of New London County announced that a deal had been reached on the day a previous, four-year contract expired.

The agreement is subject to a ratification vote among union members next week.

“This agreement contains significant enhancements including higher wages, additional vacation and paid sick time for newer employees, a longevity bonus for our long and faithful employees, a retention bonus, pension and 401(k) increases,” reads the statement, signed by union president Pete Baker and Shawn Coyne, EB’s vice president of human resources.

“A premier benefits program will continue to protect MTC members and their families,” the statement continues. “This agreement creates efficiencies and a new process to enable the construction of these critical submarines at a higher volume and velocity.”

No details of the contract were immediately available.

Formal contract negotiations began Aug. 28, with the union’s negotiating committee announcing two days later that union membership had overwhelmingly voted to authorize a strike, if necessary, to secure its demands. The strike authorization vote passed by a 32-to-1 margin.

As in previous negotiations between the parties, a federal mediator was enlisted to facilitate the contract talks.

The MTC represents nearly 3,000 shipyard workers, including boilermakers, electricians, laborers, machinists, office and professional employees, painters, pipefitters and teamsters.

Electric Boat designs, builds, repairs and modernizes nuclear submarines for the U.S. Navy, employing more than 21,000 people.

b.hallenbeck@theday.com