But Gainor is worried. It is 10 minutes to air time, and he still hasn't sat down with his guest, a mercury pollution expert. He doesn't know where she is. And when he finally meets her in the ''green room" -- a small room with a coffee pot at WATD studios in Marshfield -- he mangles her name.
''I screw up when I get on the air," he tells her. ''Just correct me if I make mistakes."
The woman looks at him. Gainor takes some notes. Then he, his guest, and his guest's husband go tumbling down the hall to the studio, where the show's other personalities, Navigator Brad and Salty Stacey, are waiting.
And this is where Lou Gainor, the 57-year-old real estate agent, turns into Captain Lou, the radio talk-show host who has become an influential voice in the state's commercial fishing industry.
''Ahoy, maties!" Captain Lou bellows. ''Welcome aboard award-winning Nautical Talk Radio, the No. 1 nautical radio program that takes you around the nautical world in 60 minutes."
Captain Lou is diligent. Even though he has been doing the show since 1991, he still writes, and reads from, a script -- 10 pages today, and typed. The script contains the nautical news of the day: everything from reports of a shark in Scituate to new federal laws that will affect fishermen.
He reads it straight -- no cheap talk-show riffs, but not like a news anchor, either. Captain Lou is animated. At times, he barely pauses for a breath. But he is also careful. The news made him what he is today.
''Lou is the primary avenue for a lot of people on the South Shore to get their fishing news, and Lou does it well," said Patrick Paquette, the governmental affairs officer for the Massachusetts Striped Bass Association. ''He'll keep it entertaining."
These days it's not uncommon to see Captain Lou talking to lawmakers on Beacon Hill or at meetings of the New England Fishery Management Council. But it didn't start that way. When the show began, it was just an idea, and a flimsy one at that.
''I said, 'What are your qualifications to do a boat show?' " recalled WATD owner Ed Perry. ''He was a little evasive about it: 'Well, I own a boat. I like boats. I can drive a boat.' "
Perry agreed to give him air time. But he didn't pay. Gainor paid him, free to make money off whatever ads he could sell. And thus was born a little Sunday boat show, focused on recreation. Soon, however, the show morphed. As he met with commercial fishermen, Gainor realized that's where the stories were, and Nautical Talk Radio took off.
''When I attended these fishing hearings, the fishermen would be debating against scientists," Gainor said. ''And when I listened to what was being said, the fishermen really knew what was happening out there. . . . I believed in them."
The station long ago stopped charging Gainor for air time. And as he approaches his 700th show, Gainor is still going strong, so passionate during show 694 that the chair beneath him shakes as he talks.
By then, Captain Lou is hitting his stride. He pronounces his guest's name correctly. And he overcomes his only mistake of the hour: when he accidentally drops every all the callers waiting on hold.
This isn't the big time. This is local radio. Navigator Brad is Captain Lou's son, and Salty Stacey is Brad's fiancee. It's family. Socks are optional here. But the man in the flowered shirt takes it seriously.
''Have a great Sunday, everyone," he says to close the show. ''This is Captain Lou. I'm off and clear."
Home: Born in Quincy, now living in Hull, near Nantasket Beach.
Family: Has one son, Brad, 34, who helps him with the radio show every week, and a wife, Ellen, of 36 years. ''She was really and truly my first mate," he said. ''You can take that any way you want, but that's the truth."
Education: A high school graduate of Thayer Academy in Braintree, Gainor went on to college, but never graduated, he said, choosing instead work in residential real estate, a job he kept for the next 35 years.
On the water: Gainor has a 36-foot cruiser, G-Force, docked at Metropolitan Yacht Club in Braintree and prefers to be on the water when he's not on the air. He has boated to Florida, but his favorite destinations remain close to home: Boston Harbor and Cape Cod. He was an active member of the Coast Guard Auxiliary from 1981 to 1985. Gainor still regularly shows up at boating events from Gloucester to the Cape.
On Beacon Hill: ''He has a reputation for knowing the issues pretty well and in depth, not just in a superficial way," said state Senator Bruce Tarr of Gloucester. ''He doesn't just report the issues on the radio and get them off in 30-second sound bites. He actually understands them."
The show: Airs every Sunday from 11 a.m. to noon on WATD (95.9 FM).