PORTLAND – Allen Cameron retired abruptly as president of Bath Iron Works on Monday in a move seen by one close observer as a shakeup of the shipyard’s leadership.

General Dynamics, the shipbuilder’s parent company, announced that Cameron has been replaced by John “Dugan” Shipway, a retired rear admiral in the U.S. Navy.

The Falls Church, Va.-based defense contractor characterized Cameron’s departure as a retirement, but a local union leader said he suspects the 57-year-old was forced out.

“I think someone told him he was retiring,” said Mike Keenan, president of Local S-6 of the Machinists union, in an interview from Bath. “As of last week, he acted as though he was going to be here for years to come, so I don’t think it was anything he was planning.”

Norine Lyons, General Dynamics spokeswoman, declined to respond to the Keenan’s remarks about Cameron’s departure.

Cameron had served as the shipyard’s president since 1996, when he was picked by former president Duane “Buzz” Fitzgerald to serve as his successor.

During his tenure, Cameron oversaw a $240 million modernization to make the shipyard more efficient by building ships on level platforms instead of the old inclined ways.

Cameron also led the shipyard through a 55-day strike in the year 2000. A year later, he and the Local S-6 officials announced an agreement to make changes to improve relations.

But Keenan said the frost between the shipyard’s unions and Cameron never really thawed.

“Allen’s not a people person. Allen puts managers in front of mechanics,” Keenan said. “If you don’t have a working relationship with the unions or its members, things go sour.”

Cameron was outside the country at the time of Monday’s announcement, according to the union president.

Both the shipyard’s incoming and outgoing presidents were unavailable for comment, Lyons said. But Cameron was quoted in a news release from General Dynamics.

“I leave Bath with deep pride and confidence in the work force, knowing that the ships we built together will serve the Navy well for decades to come,” Cameron said.

On Monday, the shipyard’s unions had a cordial meeting with Shipway, Keenan said.

The 60-year-old Shipway proposed holding meetings every other week between the unions and management, a move the unions interpreted as a fence-mending step. Cameron held those meetings only once every six months, Keenan said.

“The big test for him is the same test we gave Allen Cameron. It’s the honesty and integrity test,” Keenan said. “Now it’s time to see if he means what he says.”