FAIRPORT, Mich. — Commercial fisherman Larry Barbeau’s comings and goings usually don’t create much of a stir in this wind-swept Lake Michigan outpost, but in the past few days, his phone jangles the minute he arrives home.

Barbeau’s 46-foot boat is the offshore nerve center for an expedition seeking the underwater grave of the Griffin, the first ship of European design to traverse the upper Great Lakes. Built on orders of legendary French explorer Rene Robert Cavelier de la Salle, it ventured from Niagara Falls to Lake Michigan’s Green Bay but disappeared during its return in 1679.

Divers this weekend opened a pit at the base of a wooden beam that juts nearly 11 feet from the lake bottom, believing it could be a section of the vessel, the rest presumably entombed in mud. They picked up the pace Monday with more powerful equipment after a weekend of probing showed that whatever is buried is deeper than sonar readings indicated.

U.S. and French experts insist it is too early to say whether there’s a shipwreck — let alone the Griffin. But anticipation is building at the prospect of solving a maritime puzzle that’s more than three centuries old.

“After we get done for the day, everybody calls or comes to the house and they’re like, ‘What did you find? What did you see? Can you tell me anything?’ “ Barbeau said in a Sunday interview aboard his ship, the Viking, which holds crucial expedition equipment, including “umbilical” cables that supply oxygen to divers. “People are really interested and they’re excited to see what it is.”

His neighbors aren’t the only curious ones. The roughly 40-member expedition team consists of archaeologists, historians, boat pilots, divers, an underwater salvage crew and assorted helpers. When not on the water, they stay in cottages and tents by the lake in the unincorporated village of Fairport, in one of the most remote corners of Michigan’s Upper Peninsula.

Some are relatives or longtime friends of mission chief Steve Libert, who has sought the ship for three decades. While researching the Griffin long ago, Libert ran across Mike Behrens, a Milwaukee sheet-metal worker whose grandfather had searched the lake for chests of gold that legend says smugglers lost during the Civil War.

“I came up here one year to witness what Steve was doing, and I asked if I could dive with him,” said Behrens, 54. “Been doing it ever since. … I’ve never met anyone as good at research as him, and he’s a very ethical guy. If he says it’s the Griffin, I absolutely believe him.”

Others have come aboard more recently, including three archaeologists from France who arrived over the weekend.

The hands-on excavation work is being handled by a three-man crew from Great Lakes Diving and Salvage, a Michigan company that ordinarily deals with mundane tasks: repairing pumps or scraping zebra mussels off intake pipes.

“We’re basically underwater janitors,” said Tom Gouin, vice president of operations. The Griffin, he said, is “like a play job for us. We’re loving it.”

The team has had to adjust its strategy, as the excavation is proving to be a bigger-than-expected challenge.

Sonar scans in years past had suggested that an object similar to the Griffin’s reputed size rested about 2 feet beneath the lake floor. But commercial divers on Friday found the bottom caked with a thick layer of invasive, fingernail-size quagga mussel shells.

After tunneling through mussels, the divers began sucking away gravel and sediments, never hitting anything solid. By Sunday night, the hole reached about 8 feet below the lake bed and it wasn’t clear how far down the wooden beam extended or what it might be attached to, said Ken Vrana, the project manager.

But as more is exposed, the post appears increasingly likely to be part of a ship, said Michel L’Hour, director of France’s Department of Underwater Archaeological Research.

“We never saw a timber standing like this one,” he said. “So it’s impossible to imagine it otherwise, so one can expect that there is a hull.”

Archaeologists Rob Reedy, of Morehead City, N.C., and Misty Jackson, of Leslie, Mich., sit on the Viking and sift through material that was found in the sediment, watching for artifacts, from bronze cannons to axes or knives — “anything man-made” that would help identify a ship, Reedy said. Thus far, the only candidate has been a slab of blackened wood about 15 inches long with characteristics suggesting it might have been fashioned by human hands. Its origin remains unknown.

Visitors inspired by the long-lost ship have drifted into the area during the search, including a 9-year-old who wrote a school paper about the Griffin and men in period costumes and handmade canoes who in 1976 re-enacted la Salle’s journey across the Great Lakes and down the Mississippi River.

Carl Behrend, a folk singer and self-described “pretty-soon major movie star” who lives 90 minutes north on Lake Superior, performed an impromptu concert outside the food tent Sunday night. He said he’s composing a song about the Griffin.

“It’s rattling around in my head,” he said.