Sunlight pours through a wall of windows and warms the wooden floor of a sail loft overlooking the Damariscotta River. Sam Upton sits on a stool. With leather thimble, polyester sail twine, ultra thick needle, and a tar and beeswax cake set near his thigh, he handstitches a bolt rope for a sail destined for Nellie, a 35-foot class wooden Herreshoff sloop.

The ivory fabric billows and folds like the train of a giant wedding dress across the vast, bright floor. From time to time Nat Wilson, master sailmaker and owner of the East Boothbay shop, inspects the work of his protégé.

Nellie, an early 20th-century wooden pleasure boat, is being restored “to her original glory” at Warren Pond Boatworks in South Berwick, he says. His shop is building the sails.

The Pride of Baltimore. The U.S. Coast Guard’s Eagle. The U.S.S. Constitution. They all bear sails made in East Boothbay by Nathaniel S. Wilson, Sailmaker. Magazine covers featuring his handiwork paper the stairwell to the second-story loft. Wilson’s sails appear on boats that span the history of water navigation, from replicas of Viking ships to modern vessels. His business has occupied the waterfront here for 35 years.

But the tall, soft-spoken sailmaker, whose eyes mirror the sharp blue water and the denim he wears, would rather emphasize the challenges of running a small business at the water’s edge than talk about his talent.

“The only reason I’ve survived here is because I bought in before things really got crazy in terms of shorefront property,” he says. “At this time, a business like mine probably couldn’t start out here and make any money. Our tax structure is not favorable to businesses right on the coast.”

Wilson raised three boys in the house next door, opened his business in 1975, and in 1979 bought the shop he’d been leasing.

“I built it as I had work. It was cyclical. Costs were considerably simpler,” he says of the early years. “I’m not a big company. I usually employ two-to-three people, plus myself.”

Industrial sewing machines, hand tools that haven’t changed in 200 years, charts, drafting table, and a wall telephone occupy the shop. Here, Wilson teaches his craft to workers like Upton. Wilson avoids using the word “traditional” when referring to his method or finished product, as he feels it indicates that his profession is on the decline. And that’s hardly the case.

“There’s a demand for what we do, particularly with the increase in the number of restorations. We have plenty of work coming,” he says.

Nonetheless, his craft differs from modern-day sail building. “Our sails are cut on the floor. We still shape the sails by our eye and our experience. Everyone in the loft learns to do that. I give it the final say.”

Modern sails, by contrast, are designed by computers and cut by lasers on tables. “All decisions are made by computer programs,” Wilson says.

His sails are constructed from woven fabric, synthetic and natural, as opposed to laminated material. “Ideally, you want a cloth that holds its shape under a whole range of design factors,” he says. “You want it to be the perfect air foil. There are practical aspects, too. How many sails do you need, for instance. It’s not a perfect science.”

On the ground level of the converted barn are the business office and a rigging shop, where Tom Ward, who owns Traditional Rigging in Appleton, does custom splicing by hand.

“Because of the type of sails we build, the various rigs-they don’t fit into the modern rig design,” says Wilson. “They are 100 years old or more.”

Wilson, 62, has been building sails since his twenties. After getting his degree in fine arts from Miami University of Ohio, he joined the Coast Guard. He says the turning point in his life was the day he walked into the Coast Guard Academy’s sail loft in New London, Connecticut, where he was stationed, and discovered the work he wanted to do.

“I look at sails as a type of kinetic sculpture. It’s a pure form of functional design. There’s a big aesthetic element to sails that I try to apply to everything we build.”

Today, outside the loft’s windows, sway the masts of pleasure vessels, tenants of Ocean Point Marina just steps away. The smokestack of a ruddy tugboat, a new construction of the nearby Washburn and Doughty boatyard, pokes above the rooftops. Hodgdon Yachts sits just beyond that.

East Boothbay has always been the commercial side of the peninsula, Wilson says. “There’s been a continuous shipbuilding tradition here, with some ups and downs.” About 15 years ago, the town of Boothbay zoned the waterfront a maritime district, which protected the working harbor of this hamlet from other interests. “The community wants jobs,” says Wilson.

His shingle-sided shop, while not nearly as large or sleek as its neighbors, is not  a quaint artifact. He has taxes to pay, payroll to meet. “No two years are alike,” he says of his decades customizing sails for clients all over the world. “The biggest bumps in the road are the policies of the state and federal government that run counter to small business.”

Wilson puts in a busy week, but tries to keep weekends free. “I putter around with old cars, I like to sail, I collect old things,” he says of how he fills his spare time. He does not have a Web site or a television, but owns five antique autos. “They get my mind off thinking about the loft. It’s valves versus sails.” Two of his sons are interested in the business, when the time comes.

“There’s a great deal of satisfaction building something with your hands,” he says. “Sailmaking is a creative process. I think it pulls together all the best of design-engineering, function, and aethetics. That’s what keeps it interesting for me.”

And what inspires others. Before working for Wilson, Sam Upton was a professional sailor and boat carpenter in South Carolina. When the opportunity arose, he came north to work for the master.

“Everyone in this world knows Nat’s name,” he says. “Nat’s the guy you come to.”

Nathaniel S. Wilson, Sailmaker is located at 15 Lincoln Street, East Boothbay, ME 04544 and can be reached at 633-5071.