When they first came to town, they landed in the middle of Center City, setting up a makeshift dry dock on a vacant lot on Broad Street.

Now the Miss Rockaway Armada is testing the waters of the Schuylkill River, readying its vessels for their debut this weekend.

Part carnival, part pirate adventure, a flotilla of pontoons cobbled together with reused, recycled, and reimagined materials will set sail under the Walnut Street Bridge and loop around the river Saturday and Sunday evening.

The armada began in the summer 2006, when about 30 people channeled their inner Huck Finn by rafted down the Mississippi River, from Minneapolis to St. Louis, on boats they made from found materials. Along the way they performed music, puppet shows, theater, and loosely defined antics for the residents of riverfront towns.

Since then, they have gone down the Hudson River into New York Harbor, and crashed the Venice Biennale by floating up the Grand Canal.

Now they are on the Schuylkill.

Flotsam, jetsam, sail some

"You forget about these bodies of water, since you can't walk out onto them," said Tod Seelie, a photographer from Brooklyn who made an "organically flowing teepee" out of vegetable crates from the Italian Market. "There's something refreshing about floating down the middle of an open-air space in your city. You can see edges of society creeping along the banks."

In the lower part of the Schuylkill, past the South Street Bridge, crumbling wooden piers and stink hint at the river's industrial legacy.

"We were out in the rain last night, watching the lightning hit, the chimneys with fire spouting out the top, cooling towers steaming," said Paul Cesewski from San Francisco. "Like a ruined Oz."

Cesewski's creation is a small, three-chair Ferris wheel that spins as riders pedal a bicycle chain drive. It's planted on a homemade pontoon boat, and the whole thing is amphibious. It transforms into a trailer that Cesewski drove out from California.

The armada came to the attention of Philadelphia's Art Alliance after their two Mississippi trips. It used a $170,000 grant from the Pew Exhibitions Initiative to bring the artists here, have them make rafts out of Philadelphia salvage, and give the exhibition a name: "Let Me Tell You About a Dream I Had."

Part of that money will go toward the armada's first exhibition catalog.

Fun, but serious expression

"They've been doing so many projects that I thought it would be important to have it truly documented in catalog form, because they've never had a catalog," said Melissa Caldwell, director of exhibitions at the art alliance. "As much fun as it is, it's also serious at the same time, in terms of using sustainable materials and creating something out of nothing."

Artist Anna Ialeggio of Vermont says the motto of her home state sums up why she is part of the armada: "Unity and Freedom."

"It's deeply satisfying to have a group of people you like to build big, crazy things with," said Ialeggio, who made a "sound bower" raft that captures and accentuates the sounds of the river. "It's addictive to fall into an accidental reproduction of something you dream about. It's not possible without the danger and stupidity of the Mississippi trip. We turned into a family."

In the next three weeks, the armada will sail three times on Philadelphia's waterways. Then the rafts will be pulled apart and reimagined as an installation at the Art Alliance's gallery in Rittenhouse Square.