Classic wooden boats under sail, snug harbors, the open sea – Loretta Krupinski has painted marine scenes for a quarter century. But in the past year, she has discovered a particular focus: Rockland’s once-bustling waterfront.

She has painted Maine for years, but began to be bored by ubiquitous renderings of the rocky coast. “I thought, ‘maybe I need to challenge myself, to spin off in another direction.’ ” In what she describes as a moment of synchronicity, she walked by the Island Institute in Rockland and noticed an exhibit of old photos taken along shore. “It was an epiphany,” she said.

She has undertaken the painstaking project of painting 13 historically accurate scenes of the city’s commercial waterfront from archival black-and-white photos. When she adds color, it’s an educated guess, since there is often no way to know the colors of boats and buildings, or the caps the fishermen are wearing as they unload a lobster smack from Vinalhaven. One lobster is in mid-air as it’s tossed into the floating car.

There is no guessing about details. Krupinski researches the historical period, and brings her own nautical knowledge to bear on items such as deadeyes in a schooner’s rigging.

“It’s been extremely challenging. There are times I said, ‘why am I doing this?’ I can’t believe no one has ever done this before. This is more than just lighthouses and spruce trees.” For Krupinski, who is inspired by three generations of Wyeths and artists such as Rockwell Kent, there is a special chemistry between herself and the scene she paints. “There’s always that sense that I am there, when I’m putting in the color – it’s like stepping back in time, stepping inside my painting.”

Krupinski’s paintings are timed for exhibit during Rockland’s 150th anniversary this year, and her work goes on display at Art of the Sea gallery on Main Street, in a one-woman show, opening July 28.

One photo depicts the Rockland six-master MERTIE CROWLEY, another a coastal packet the numerous granite wharves jutting into the harbor. Yet another captures dories loaded to the gunwales with herring. Ships brought in fish and carried locally mined lime, ice and granite to faraway ports.

Studying black-and-white photos obtained from the Rockland Historical Society and personal collections, she can tell whether it’s summer from foliage. From a lifetime on the water, she knows the colors of glassy calm, squally wave and overcast sky. Growing up on New York’s Long Island, and later living in Old Lyme, Connecticut, she sailed and painted, taking time to earn a degree in fine arts from Syracuse University. She is a fellow of the American Society of Marine Artists.

“I believe that artists have an important role in preserving the landscape, whether it is from the 19th or the 21st century,” she said, even as development alters that environment. She remembers, years ago, painting fishing boats in Gloucester. “I thought those old wooden draggers would be there forever.”

A petite woman who exercises to stay fit, Krupinski seems to have irrepressible energy and ability as she turns out canvas after canvas. She has exhibited at Mystic Seaport’s Maritime Gallery and others around the country. She has 25 children’s books to her credit plus another in the works. She lives in South Thomaston with her husband, Bill Bailey, retired from a career as a national sales manager. Their house is called Tide’s End; its rooms are decorated with maritime art and ship models.

She plans to keep on painting from historical photos. “I’m very excited. I’m thinking that I can’t live long enough to paint everything.”