They used to call him Dennis the Menace, the earnest, grinning 11-year-old who wouldn't leave the San Diego yacht racers alone.

Today, it was Dennis the King, ruler of the yacht-racing world after Dennis Conner piloted a blue 12-meter called Freedom to the 24th successful defense of the America's Cup, yacht-racing's most coveted jewel.

In a breezy, rainy, dark Rhode Island Sound, Conner nosed Freedom over the starting line a boat-length ahead of the challenger, Australia. He had the race in hand within 10 minutes as he pushed his white oncoming rival off the wind and charged ahead of her, never to relinquish the lead.

The blue boat increased her edge on every successive leg of the race but one. When it was over, 3 1/2 hours and 24 miles later, Australia was a distant, out-classed second, 3 minutes 38 seconds behind, and Freedom had taken the best-of-seven Cup series, 4-1.

Conner was given a hero's welcome by adoring Newport. There was a brass band playing, "Hail, Hail, the Gang's All Here" when the yacht returned to port under tow. At least 1,000 well-wishers jammed the docks. There was champagne and a military escort of Coast Guard fireboats, cannon fire and horns and flags and a great, happy tossing into the drink of captain and crew and syndicate members.

The celebration may have been doubly delirious, because for the first time in a decade there was actually some concern for the safety of the Cup the United States had never lost in 129 years of competition.

This was not the walkway victory that had been expected. The Australians managed to win a race in the final series, the first time that had happened since 1970, when the same Australian skipper, Jim Hardy, piloted Gretel II in her 4-1 loss to Intrepid.

Today's failure marked Hardy's third and last attempt at the Cup. "Jim Hardy doesn't want to be a four-time loser," said the gentlemanly skipper afterward. "I will not sail another challenger."

This year, Australia was a match for Freedom only when the wind didn't blow. Her victory in the second race of the series came by 28 seconds, when the breeze dropped to minimum levels and the two boats finished the race barely within the 5 1/4-hour limit.

There ensued in the races much politicking over the selection of lay-days, of which each boat was allowed three. The Aussies tried to take days off whenever the wind threatened to blow, the Americans whenever light airs were predicted.

In the end, the overpowering odds, given the nature of autumn in New England, were with Freedom. She beat Australia by a commanding 3:48 in moderate airs Tuesday to run the score to 3-1, then came back today in a stiff, 15- to 18-knot blow out of the southeast.

It was raw, New England fall weather was a spitting rain -- no fun for spectators. There was mostly an empty void on the water where the spectator fleet usually sits. Conner's final triumph was witnessed by very few. They honored his achievement at the finish with loud horns, cheers and a smattering of fireworks. The real show came later in jammed Newport Harbor.

It was a great triumph for Conner, who is far from the mold of an America's Cup skipper. Like Ted Turner, who defended the Cup in Cour Courageous in 1977, Conner is something of an outsider among the scions of the New York Yacht Club, which mounts the defense every three years.

He learned his sailing as a hanger-on at the San Diego Yacht Club, where he spent every spare moment as a child. He never owned a boat until he was 28 years old.

Connor lived just up the street from the club and consumed the largest part of his youth hanging around, picking the brains of the best sailors there. They called him Dinnis the Menance and, when he finally reached the point in his life where he was competing for one of the great prizes in competitive sailing -- the Star world championship -- he captained a boat called Menace. And won. Twice.

Connor was aboard Courageous as starting-line helmsman when she defended the America's Cup successfully in 1974. He did not sail in the 1977 Cup series.

His drive for the Cup this year was marked by unprecedented preparation and the most well-managed program in the history of the Cup.

The Freedom campaign started 2 1/2 years ago. Conner was selected as helmsman by the Freedom/Enterprise syndicate. He went through more than 100 applicants in picking his crew and sailed with them for some 18 months, about three times the normal practice regimen.

Freedom demolished both her competitors for the right to defend. In trials to select a U.S. defender this summer, she won 44 races and lost onnly four to the aging Courageous and Clipper, a new boat.

She walloped Australia on their first outing by 1:52, leading from start to finish in moderate breezes.

The second time out, Australia's desperate, last-minute gamble to find a winning edge paid off. The Aussis had built in secret, and installed one week before the Cup series, a bendable mast that increased the boat's sail area and gave her an advantage in light winds.

In the second race, the wind died with Freedom in the lead. Australia swept past her in fluky, light airs and had built a commanding lead when the race was abandoned after exceedinng the time limit. Next time out, the wind started light and stayed that way. It was the best race of the series, with the lead changing hands twice and Australia finally winning by 28 seconds.

"The loss really humbled us," said Dennis Durglin, tactician aboard Freedom.

Conner didn't stay humbled long. Freedom won the third race by 53 seconds despite the fact that two of her sails blew out during the contest.

Then came the 3:48 win and, finally, today's deciding victory.

Conner consistently won the starts of these races and Freedom showed convincingly superior speed on the upwind legs, which make up two-thirds of these match races.

She was faster across the board in real sailing winds and Australia never had the time to develop the advantage her ultramodern rig promised.

In the end, Australia was just another statistic in the long U.S. domination of the America's Cup.

And Dennis the Menace was Dennis the King.

Tonight, Conner said he was not sure whether he would be back to defend in 1983, but George Jewett, who helped organize the Freedom syndicate, said, "Dennis will be back."

Alan Bond, who organized the Australian effort, said he definitely will be back and is already planning construction of two new boats.