BATH, Maine — Bath Iron Works employees flowed down Washington Street late Thursday morning in a large current of vocal protest, opposing the way the company’s largest union says it has been treated by BIW.

Jay Wadleigh, president of the International Association of Machinists and Aerospace Workers Local S6, said the rally was to promote solidarity during the year before the union’s contract expires.

“We do expect it may be difficult, [but] we are solid,” Wadleigh said. “The union is behind its leadership, and the company is going to have to negotiate with us and not dictate to us.”

After decades of a relatively peaceful relationship, tensions between Local S6 and management have flared in recent months as the new president of BIW, Fred Harris, has proposed changes including outsourcing work and cross-training employees. Harris argues the changes will increase efficiency and keep the costs of building destroyers competitive.

But the union disagrees with the changes, resulting in accusations, third-party arbitration and, most recently, a federal lawsuit charging BIW with violating its contract with workers, the Bangor Daily News reported.

“They need to abide by the contract, stop misleading the media and just work with us so we can get the costs of these ships down,” Wadleigh said Thursday. “Shipbuilding dollars are getting thinner and thinner, and we are going to have to find ways to do things smarter and cheaper, there’s no debate over that. We’re the best shipbuilders in the world. We want to work. We just want to be treated with dignity and respect and be negotiated with and not dictated to.”

In March, nearly 1,000 members of Local S6 marched the length of the shipyard at midday to rally support and to protest the proposed changes, the Bangor Daily News reported.

Wadleigh said he hopes Thursday’s rally will force the company to return to negotiations.

With so many families reliant on BIW, Wadleigh said, “It’s in everyone’s best interest if we can find amenable ways to come through this stuff. The answer isn’t by going to federal court; the answer isn’t by taking everything to arbitration.

“As this contract gets closer, the company needs to know that we — and I mean all of us — will accept nothing less than a fair contract,” Wadleigh told the crowd gathered outside the shipyard on Thursday.

Reached for comment on Thursday, BIW spokesman Matt Wickenheiser referred to a company bulletin issued Wednesday.

“BIW must work together as one yard to become more efficient, affordable and competitive in order to win future work and maintain current employment levels,” the bulletin states. “If the company does not win future work, such as the Coast Guard’s Offshore Patrol Cutter Program, BIW faces the loss of over 1,000 jobs.”

BIW can only reduce costs and stay competitive “by making common-sense changes that eliminate production bottlenecks and reduce wait times — potentially saving thousands of hours each year. That is where we must all focus our efforts,” the bulletin states.

According to the company, BIW hired about 600 tradespeople in 2014 and is slated to hire another 500 this year.

The company has more than enough core shipbuilding work for the workforce — we are trying to do that work more efficiently,” the bulletin states.