Harold Seigel, an otherwise mild-mannered dentist from Falls Church, speaks in the measured tones of a professional when describing a work life of inspecting molars and performing root canals.

But talk to him about Good Vibrations, his 34-foot powerboat, and his reserve begins to slip away. Better yet, hang with him on a sultry night on the promenade at Washington Harbour in Georgetown, the women and cocktails swirling about, and he is a man fully liberated from his dental office.

"Tarzan!" Seigel yelped, spotting an old friend, a tall, handsome man with a ponytail.

It was nearly 9 p.m. on a Friday, but Seigel already had been there for hours, arriving aboard Good Vibrations in the afternoon to get a spot along what is perhaps Washington's most gilded slice of boating real estate, a 600-foot sea wall that runs along the promenade.

Here, with the Kennedy Center as glowing backdrop, the amateur captains and their crews of pals and hangers-on float away the hours on vessels with such names as Shameless and Audacious and Suits Us, drinking beer and cognac, rocking to Springsteen and the Beach Boys and ogling the revelers parading along the promenade.

The wall is not long enough to accommodate all the boats, so some are tethered to others, sometimes extending into the Potomac River in a row of four or five or even six. But the spot everyone wants is along the wall, so the boaters and their guests can slip back and forth easily between the vessels and the array of outdoor cafes, such as Sequoia and Tony and Joe's Seafood Place.

"It's a status thing," Seigel said, explaining that capturing a perch suggests a life of privilege, that "you were able to get out of the office early enough to get to the wall."

Seigel likes to describe his regular outings to the harbor as something on the order of good, wholesome fun, particularly if somebody is jotting down his perceptions. The dentist's friends are a tad more freewheeling with their odes to life on the promenade.

Tarzan, otherwise known as Bill Pierce, 39, said he spent many a night at the harbor once upon a time for one main reason: to meet women. "If you needed to rebuild inventory, this is where you came," he said. He described the boats as "floating bars and bathrooms with propellers."

Pierce said he does not spend as much time on the promenade these days, the reason being the woman who stood next to him, his wife, Bernadette. "He doesn't need to pick up girls anymore," she pronounced before hooking an arm through his and slipping away for a drink.

A few yards away, Matt Martelli, 32, a computer programmer, sipped a rum and coke by his 32-foot powerboat, Colonel's Lady, and rhapsodized about the close ties he has developed with those he regularly sees at the harbor.

"I don't know Guy's name; I don't know what he does," he said of the man he was talking to at the moment. But on the water, he said, he would do anything for him. "We're brothers who are boaters."

Brotherhood might be important, but Martelli's main concern that night appeared to have been more related to the sisterhood, in particular the gaggle of women who crowded onto his craft. At one point, he stood on the promenade, shirtless, trying to attract more to his party.

"Hello, girls. Can we offer you a beer?" he asked, spotting a trio of young women wearing tank tops and carrying small purses.

They stopped, each introducing herself as "Jessica." He kissed their hands, furnished them with beers, and they went off to join the crowd on his boat, which included a slew of buddies who came to meet up with him.

Martelli smiled. "I'm an enabler," he said.

The boat owners form a predominantly male crowd, but there are a few women behind the wheels, including Kimberly Newman, 44, a quality assurance director from Alexandria. When she broke up with her boyfriend a couple of years ago, Newman said, she found herself boat-less. So she went out and bought the Livin' Nauti, a 47-foot yacht that is larger than most of the crafts that regularly pull up to the harbor.

"I didn't want to go through those little boats," she sniffed.

Yes, size matters at Washington Harbour, at least along the sea wall.

Alan McGillis, owner of a computer services company, sat on his 46-foot yacht, christened Charis by the previous owner in appreciation of a Playboy model, and said that all boaters are equal on the water.

Then he contradicted that, suggesting that he wasn't much interested in the small-boat crowd.

"If you have a 46-footer, you don't hang out with the 10-footers," he said, standing below deck in his galley, as a few friends lounged on deck.

He described the scene as a "second fraternity house in life; it brings you into an elite."

"It's a babe magnet," he said of his yacht. "The bigger the boat, the more people cling to you."

As he spoke, the clock ticked toward midnight. On the promenade, a man sang Bob Dylan songs, and the crowds mingled at the cafes. The three Jessicas emerged from Martelli's boat, giggling as they headed for home. Tarzan puffed on a cigar.

Harold Seigel sipped a beer outside Nick's Riverside Grille, appearing as though he had no intention of climbing back aboard Good Vibrations and leaving anytime soon. There would be no molars to check and no root canals to perform for at least another two days.

"It's exciting," he said of his little world on the water, his eyes following an attractive woman as she made her way toward the bar.

Fourth of July weekend was a prime party time for boat owners and guests in front of Sequoia restaurant at Georgetown Harbor.Alexis Katsarelis and fiance Omar Balkissoon of Sterling enjoy the night.As boat owners compete for prime real estate along the Washington Harbour promenade, kids, couples, strollers and dog walkers enjoy life on land.Matt Martelli welcomes aboard Jen Marie Parker, left, of Vienna and Lori Sheppard from the Dulles area.