The dance rehearsal might have looked like any other: One dancer bent another into a cheerful spin as she marked through a jazzy number; a chorus of male hoofers soft-shoed in a line behind them. And then dancer Rob Besserer casually adjusted his anti-seasickness bracelet.

Such is life when rehearsing on a barge. Last week, down at Miller’s Launch on Staten Island, the cofounder of the avant-garde Mabou Mines company, Ruth Maleczech, was staging the company’s “Song for New York,” which begins performances on Friday on a barge stationed off of Long Island City. Last week’s rehearsals took place on a medium-size barge, one more often used to transport equipment to nearby tankers than shuttle downtown theater troupes. Secured in the bay by long telephone-pole shaped anchors called spuds, the structure nonetheless bobbed gently in the water, and the company was still acclimating. Due to a week of rain, the dancers had been kept indoors, and no amount of practicing on stationary scaffolding could prepare them for a buoyant base.

“Song for New York” is a multi-disciplinary piece, the kind for which the Mabou Mines troupe, which has built a reputation incorporating dance, theater, puppetry, and song, is known. Ms. Malaczech said she started dreaming of a great hymn to the city after the events of September 11, 2001. While standing by the Wall of Remembrance by St. Vincent’s Church, she found herself repeating two randomly selected names to herself in a kind of incantation.” Then I started to read the great poets who have written about New York — Walt Whitman, Hart Crane. But those are over a century old,” she said. So she commissioned new interstitial text fragments that describe New York’s history and arias about each of the five boroughs from Karen Kandel, a longtime collaborator, Migdalia Cruz, Patricia Spears Jones, Maggie Dubris, and Imelda O’Reilly. All of the pieces were then set to music by Lisa Gutkin.

Each day of the five-day performance is dedicated to a different borough, although the company performs the entire song-cycle each time. Much is made of time passing: When audience members arrive, they can have their pictures taken with a pinhole camera. The slow development of the image is coordinated to take roughly the same time as the sunset. Only then does the piece begin.

But sunset or no, Ms. Malaczech denies that the piece can be considered nostalgic, since she believes “that implies longing for a somehow different New York.” Indeed, the experience of directing “Song” has sharpened her feelings about the city. “We couldn’t even tell people about the dates of the show until we had consulted with the Parks Department, New York City Police, the Fire Department, a surveyor and the Coast Guard. We had to take out $3 million in insurance policies, and indemnify everybody,” she said.

And even now, no one knows exactly how the evenings will work. Nearly every design element will be different in situ, and the barge won’t head upriver until the day of the piece’s first performance. At Miller’s Launch, fog rolled in, turning the backdrop — a study in sulfur lamps, the Intrepid, and the Verrazano-Narrows Bridge — into a Turner painting.

But when the company is in place just off Long Island City’s Gantry State Park, the view will become significantly more pastoral. Weather and landscape will even change how microphones work. The sound co-designer Robert Kaplowitz seemed resigned but cheerful, even as he and the other technical crew scrambled to cover their equipment after the rehearsal. “We keep saying, ‘It’s just like being on tour, only you don’t have to go to Duluth,'” Mr. Kaplowitz said.

Until September 9 (50-50 Second St., Long Island City, 718-786-6385).