PORTSMOUTH, N.H. — A replica of a historic barge-style boat that sailed the waters of New England since the late 1600s set sail for demonstration cruises during the weekend.

The 64-foot Piscataqua, a flat-bottomed gundalow, sailed from Prescott Park in Portsmouth, N.H., three times Saturday. The boat’s decks were open to the public for the first time since its 2011 construction for the cruises in the Piscataqua River, which separates Maine and New Hampshire.

The boats’ flat bottom was designed for low tide, mud flats around the New England area. Their high-masted, lateen sails were designed to collapse to the deck so they could go under bridges.

The Gundalow Company, a nonprofit organization in Portsmouth, has raised close to $1.2 million over the past decade in order to replicate gundalows. The first replica was built in 1978.

“Gundalows are specific to the area. Portsmouth is the only place in the world that you can sail on one of these boats,” Molly Bolster, executive director of the Gundalow Company, told Foster’s Daily Democrat.

Gundalow staff was impressed at the turnout during the Piscataqua’s first day open to the public.

“This project has really become part of the community,” Bolster said. “Nearly 12,000 visitors came to watch the boat being built, while hundreds of others have watched from land as we set sail. It’s fun to see the community really back up our vision.”

One of the passengers, Kent Hammon of Stratham, N.H., said he got more than the slow-paced ride along the river he was hoping for.

“It gives you a view of Portsmouth that you don’t see very often,” Hammon said.