The advertisement looked phonier than a midsummer Christmas sale. It offered day and overnight sailing on the Chesapeake Bay, in a 37-foot-long sloop worth $75,000, for free. Absolutely, fine-print, free.

"People wanted to know what the catch was," says Ron Vergagni, 58, the captain and owner of the Prima Donna II, who has been playing Santa Claus on the Chesapeake for most of the last two years. "They just thought it was too good to be true."

Vergagni's offer was real. To qualify for a Coast Guard license as a charter captain, he needed 365 certified days of sailing. He couldn't charge a fee until he got the license. But he didn't see any reason to sail alone. So he invited the world to come along for the ride.

"It was just a little ad," says Vergagni, a trim, mildly gregarious man who has been an officer in the navy and army, as well as a federal bureaucrat. "But my telephone never stopped ringing. I was inundated."

Sailing is to the Chesapeake what skiing is to Colorado. The wind and the water have a stylish marriage here. There are enough coves, creeks, rivers and islands to explore along the 168-mile length of the bay to keep a weekend sailor wide-eyed for a lifetime.

"You can sail every day for years and never see it all," says Vergagni, who spent 22 years in the military and 17 years doing government work as a civil servant before taking to the sea full-time in 1980. "When I sail on the bay, I feel like I'm sailing into history."

If you don't have the time, the expertise or a boat, you still can ride the Chesapeake's wind. You just need money. There are a dozen sailboats with captains for charter on the bay.

Until June, when Vergagni finally earned his charter license and began charging a fee ($150 a day during the week and $200 a day on weekends for parties of up to six), he was certainly the best bargain. From his dock in Rock Creek, on the western shore of the Chesapeake between Baltimore and the Bay Bridge, Vergagni is just a few hours sail from the Inner Harbor, Annapolis or the Eastern Shore. Often he would take guests to places he knew only from charts. And he would teach them to sail on the way.

Vergagni has hosted graduation parties, nurses and newlyweds on his boat. He has seen romance bloom and bust when a singles club spent a weekend aboard. What he sees mostly is wired workaholics who use the boat as a floating sanitarium.

"So many people are under pressure, in Washington, D.C., particularly," he says. "This is good for what ails you. It's a tonic. I can see the difference between people when they come aboard and when they leave. It's fantastic."

Vergagni started sailing in San Francisco Bay when he was a 14-year-old Sea Scout. He joined the navy at 17, and spent the next eight years on battleships, troop transports and amphibious vessels in the Atlantic, Pacific and Indian oceans. He switched services after World War II so he could stay in Japan. Sometime after that -- he can't quite figure out how -- he lost touch with the water.

"In 1976 I started sailing again," says Vergagni, standing behind the wheel of his boat while a 10-knot wind fills the sails. "The more I sailed, the more I realized this is where I belong. I said, 'Why have I been away so long?' "

Vergagni is the Felix Unger of the bay. His boat is spotless. His galley has more utensils than many restaurant kitchens. His sails look as though they get scrubbed down every day. His 37-horsepower diesel engine is so shiny clean, you almost need sunglasses to check the oil.

"If things didn't go back where they came from there would be chaos," says Vergagni. He has been in enough storms to know they are poor times to be looking for a winch handle or untangling rope.

Three years ago Vergagni rode out a storm on the bay with 90-mile-an-hour winds. He had four passengers aboard, all on a sailboat for the first time. They never took their eyes off his face.

"I was too busy to be scared," says Vergagni.

If the weather is sometimes temperamental, Vergagni swears his passengers never are. Many write him letters, some send gifts. He has attended the weddings of people who fell in love on his boat.

"I have never had one bad incident with people," says Vergagni. "Everybody has been wonderful. It renews your faith in human nature. There are a hell of a lot of nice people out there."