The decades-long effort to revitalize this Navy town climaxed today with a carnival of marching bands and bellowing tugboats celebrating the opening of a $13.5 million riverfront marketplace created by nationally acclaimed urban developer James Rouse.

A crowd of 10,000 jammed the specialty shops, boutiques and restaurants in the new two-story Waterside pavilion that Rouse calls a "festival of life." It is a scaled-down version of his earlier projects at Faneuil Hall in Boston and Harborplace in Baltimore.

City leaders, who have pinned their hopes on Waterside as a magnet for Norfolk's once-seamy downtown, turned out en masse for an opening ceremony that, despite occasional rain and an earlier boycott threat by black leaders, was virtually flawless.

Just as Linda Robb, wife of Virginia Gov. Charles S. Robb, prepared to christen the market with champagne bottles of confetti, a flotilla of some 30 tugboats--described by the city as the largest tugboat parade in history--chugged up the Elizabeth River. Cannons were fired, balloons were unleashed and the tugboats let loose with a five-minute-long deafening blare of toots and whistles.

Mayor Vincent J. Thomas, who had pushed the project over the protest of the City Council conservatives, felt vindicated. "This acts as a symbol to all the people of Norfolk that our city can be rejuvenated," he declared.

"It's a touch of class for old Tidewater," added State Del. Thomas W. Moss, a lifetime city resident and another booster of the project. "It's going to bring Norfolk back into the 20th century before it has expired."

The celebration comes at a critical juncture for this community of 267,000. For years city officials have struggled to breathe life into a moribund riverfront, while middle-class professionals fled south to fast-growing Virginia Beach. Two years ago, the Beach eclipsed Norfolk as Virginia's largest city, a grievous wound to civic pride.

More recently, the city has been racked by controversy over a proposal to end a crosstown busing plan that supporters felt had successfully integrated the public schools. Critics argued the busing had fueled the suburban exodus.

Last week, the busing dispute came close to disrupting the Waterside hoopla. Black leaders threatened to boycott today's ceremonies unless the school board backed off its earlier vote to end busing this fall. So dear was Waterside to the hearts of city officials that the board quickly voted a one-year delay.

"We felt that the city was more concerned about economic development than the rights of black children," said the Rev. Joseph N. Green, the city's black vice mayor. Had the blacks not made their threat, "they the school board would not have changed. I have no doubt about it."

Green and other black leaders who were on hand today, emphasized that they have no quarrel with Waterside itself, given its creation of 1,000 new downtown jobs and official estimates that it will pump $120 million into the local economy during the next 30 years.

Still, there are skeptics who question the large public investment required of the city to entice Rouse, the developer of Columbia, Md.

Under a complex financing scheme, the city put up the entire cost of the project, including $9.8 million of its share of federal redevelopment funds.

On top of that, the city will pay Waterside Associates (a partnership between Rouse's Enterprise Development Co. and local developer Harvey Lindsay) a management fee of $225,000 a year. Any profits will be split fifty-fifty between the city and the Rouse-Lindsay partnership.

City Council member Claude Staylor notes that this is the only one of Rouse's heralded projects in which he hasn't put up a dime. "I'd say he's doing quite well," said Staylor. "If we treated every developer this way we'd be in serious trouble."

For city fathers, who have agonized over the downtown's plight for decades there are few doubts. East Main Street in downtown Norfolk was known as one of the country's more notorious red-light districts, an array of burlesque shows, tattoo parlors and houses of prostitution that catered to sailors from the naval base. Old rotting warehouses dotted the waterfront.

"It didn't bring credit to the community at all," said banker Doyle Hull, as he recalled the old downtown. "It was the seamy side of life."

In the 1950s, the whole area was razed as part of the federal redevelopment effort and the arduous task of rebuilding began. Gradually, during the late 1960s and early 1970s modern complexes such as the skyscraping Virginia National Bank Building, the Scope Convention Center and the luxury Omni Hotel, moved in. But it was not enough to bring downtown alive.

"People would work in office buildings during the day and then go home at 5 p.m.," said Hull. "At night, it would become a ghost town."

Enter Rouse. Hull recalls the day four years ago when he, Mayor Thomas and other city leaders paid the developer a call at his vacation cottage in Virginia Beach.

"We went out there one weekend and he was just returning from the beach with a load of fish," Hull said. "His reaction was: 'Why me?' He said he was awfully busy."

Nonetheless Rouse, who had tried and failed to develop a downtown shopping mall in Norfolk nearly 20 years earlier, acquiesced, provided the city would meet his financing requirements.

Other downtown revitalization projects--a World Trade Center office building, luxury condominiums and town houses--are under way and city officials are optimistic that Waterside will do to Norfolk what Harborplace did for Baltimore.

Rouse, perhaps the country's leading apostle of urban renaissance, echoed that optimism today at a breakfast gathering with civic leaders in the exclusive Harbor Club.

Waterside, he said, was designed to preserve the distinctiveness of Norfolk's relationship with the water, with a miniaquarium, decorative boat figureheads, and ship models.

The underlying concept is the same as Harborplace and his other creations, to create a "festival of things people would like to do in their normal lives," he said.

"The downtowns of America are heading for rebirth," Rouse added. "The transformation of the American city is going to be at least as dramatic as the suburban explosion of the 1950s and '60s. And now, we are seeing the beginning of that." CAPTION: Picture, A juggler entertains visitors during yesterday's festivities opening Norfolk's new $13.5 million marketplace, The Waterside, on the downtown waterfront. AP