Dozens of boats zipped across Casco Bay during the Maine Lobster Boat Races on Saturday. Only one had a purple bottom.

That boat, a 32-footer with a powerful diesel engine, belonged to Jeremy Beal, 45, a large, soft-spoken man who comes from a long line of boat builders and lobstermen.

“See, I grew up right in it,” he said between drags of a cigarette while leaning against the rail of his boat on the evening before the big race.

For decades, Mr. Beal’s father, Wayne Beal, and an uncle, Calvin Beal, have built boats used by commercial fishers up and down the Maine coast. After years spent learning the family trade, Jeremy took over his dad’s business, Wayne Beal’s Boat Shop, in Jonesport, a seaside town more than 200 miles northeast of Portland.

“I bought the boat off my father,” Mr. Beal said. “It was his last power boat. He’s retired out of the boat shop. I won’t sell the boat unless I have to. Just for the fact that it was my dad’s.”