enlarge Jill Brady/Staff Photographer

Boatyard employees, from left, Fred Brooks of Phippsburg, Tom Adams of Bath and Bill Hoyt of Chamberlain, look over the wreckage Saturday.

enlarge Jill Brady/Staff Photographer

The hulls of two tugboats that were under construction are all that’s left after Friday’s fire at Washburn & Doughty Associates in Boothbay. Firefighters, worried that the structures could topple over, kept their distance Saturday. The fire’s cause is under investigation.

enlarge Jill Brady/Staff Photographer

East Boothbay firefighters hose down hot spots Saturday at Washburn & Doughty boatyard. Firefighters expected embers to smolder for several more days.

BOOTHBAY — The big worry for firefighters trying to flush out the embers that continued to smolder in the wreckage of the Washburn & Doughty Associates shipyard Saturday was the possibility that the two big tugboat hulls would topple over and tumble like stacked dominos toward the sea.

Boothbay Fire Chief Dick Spofford said it wasn’t obvious what was holding the metal structures up.“We have to stay far enough away in case they tumble over,” said Spofford.

Firefighters aimed hoses at the hulking pile of rusted steel that was all that remained of the building where three tugboats were under construction when a fire broke out just after 9 a.m. Friday. The blaze quickly engulfed the assembly building and spread to several nearby piers and storage buildings hundreds of feet away. All of the workers got out of the building unhurt and none of the firefighters was seriously hurt.

How the fire started is not yet known. The State Fire Marshal’s Office is still investigating, Spofford said.

But workers said small fires were sometimes triggered by sparks from the welding, cutting and grinding that went on in the 100-year-old wooden structure. They said workers were on break when the fire started, setting off the sprinklers.

On Saturday, the mood at the shipyard appeared to be one of relief that no one had been hurt, and hope. The shipyard employed 85 workers who make tugboats almost exclusively for Moran, a Connecticut-based company that runs tugboat services in ports up and down the East and Gulf coasts.

Workers do not yet know their fates although shipyard owners Bruce Doughty and Bruce Washburn were vowing Friday to rebuild. Workers have been called to a meeting at 7:30 a.m. Monday where they may learn answers to such questions as how soon the yard might be rebuilt, and whether they will get paid.

Pipe fitter Bill Hoyt of Chamberlain, who took Friday off to drive his nephew to the Portland International Jetport, said he was not worried about his own fate.“I am single with no obligations and will be fine. But I worry about the guys with families,” said Hoyt, who has worked at the shipyard for 21 years.

The shipyard teemed with activity. Workers scrambled to put the finishing touches on an articulated tug and barge due for delivery in a few weeks. During the height of the blaze it was towed into the bay to avoid damage.

Two insurance claims investigators from The Travelers Cos. were trying to determine whether the two tugboats under construction in the assembly building were salvageable.

Maine Department of Environmental Protection staffers were inspecting the water and piers for leakage. Barbara Parker, director of the division of response services, said it appears there were no major spills. There is some concern about the paint shed, which burned to the ground.

“We will look but it is still unsafe,” Parker said.Chief Spofford said the sheer intensity of the blaze actually helped mitigate environmental contamination. He said any toxic chemicals burned up instead of leaking into the runoff from the fire hoses.

A steady stream of onlookers arrived at the scene by boat, foot and automobile.

Sally Barker of Cape Elizabeth had watched the smoke as she motored up in her boat from South Portland for a stay at Boothbay Harbor.

She and her husband borrowed a truck from Brown’s Wharf Inn and Marina to see the source of the smoke. Boothbay resident Bonnie Allen, whose husband works at Hodgdon Yachts next door, said she had to see the scene for herself.

The fire was the talk at the East Boothbay General Store where many of the shipyard workers regularly buy lunch. Owner Elizabeth Pochee said she would feel the loss of their business.

During the height of the blaze the narrow streets were clogged with fire apparatus and emergency vehicles brought to the scene by about 125...