The term “concert cruise” typically conjures thoughts of Hawaiian-shirted Jimmy Buffett cover bands and Pat McCurdy types, but for its 2010 schedule the Milwaukee Boat Line has played against type. Rather than recycle headliners from the city’s summer festival circuit, the party-boat purveyors instead tap the city’s club venues, booking a lineup that includes many of Milwaukee’s best indie-rock bands.

A four-piece with a feral, rockier update of The Smiths’ melodramatic guitar-pop, The Celebrated Workingman soundtracked a two-hour tour of the Milwaukee waterways Saturday night. They performed on a makeshift stage on the boat’s stern, which they had decorated with Christmas lights, using amplifiers that sat precariously on stacked deck chairs.

The voyage was scenic and pleasant, with lovely views of the Milwaukee skyline and riverfront and the South Shore Frolics fireworks, though the band and passengers alike were caught off guard by how rocky the waters briefly became once the boat left the Lake Michigan harbor.

“This is really hard,” singer-guitarist Mark Waldoch said with a laugh between songs, as the band spread their legs to steady themselves, and the woozy, merry crowd clung to each other’s shoulders for balance. Ultimately, nobody took a tumble, but a few came close. (The post-rock band Collections of Colonies of Bees, playing the Iroquois’ sister boat the Voyageur at the same time, sadly didn’t fare as well—one of their amps slid into the lake.)

The Celebrated Workingman used their lengthy set time to preview several new tracks, each a jubilant swell of emotions conducted by Waldoch’s massive bellow. Staples from the band’s 2008 debut, Herald the Dickens, invited sing-alongs from the tightknit crowd, as did covers of The Cure’s “Boys Don’t Cry” and the Muppets’ “Rainbow Connection,” which further lent to the evening’s camaraderie.

The closest the set got to conventional boat fare was a brief interpolation of “Crimson and Clover” played toward the night’s end, as the boat returned up the river toward its dock, but with Waldoch’s pugnacious wail—which took on a particularly raw edge through the boat’s fussy PA system—there was no risk of patio diners at Ryan Braun’s Waterfront mistaking the group for an oldies cover band. The diners gawked at the Iroquois with a mix of curiosity and amusement, as well as the natural jealousy that most everybody feels when they gaze at a passenger boat from land.

Upcoming Iroquois concert cruises include Decibully (July 15), Burgundy Ties (July 16), The Etiquette (July 17), The Wildbirds (July 22), 5 Card Studs (July 23), Fever Marlene (July 24) and Revision Text (July 29).