When folksinger Tom Chapin first laid eyes on Battery Park City’s wide-open parks in the nineties, his own grassroots instincts kicked in: He envisioned a music festival. The idea went nowhere until a week or so after 9/11, when he was astonished to hear that the parks remained virtually intact, save for a layer of ash. A few months later, he and the coordinators of the Battery Park City Parks Conservancy gave birth to Harmony on the Hudson, a free family-music festival, now in its fifth year. On September 10, the Grammy-winning guitarist will perform the most popular hits from his collection of children’s CDs, including “Family Tree” and “This Pretty Planet,” the song that John Glenn used in 1998 to wake up his fellow astronauts on the space shuttle. Also performing will be Cajun combo Beausoleil Avec Michael Doucet and the Klezmatics, a six-piece band that infuses centuries-old Eastern European Jewish melodies with lyrics borrowed from the likes of punk rock and Woody Guthrie. Between sets, percussionist David Pleasant will attempt a parkwide drum circle—a respectable undertaking with a crowd upwards of 5,000—while the inspiring middle-aged Double Dutch Divas will show off some fancy footwork with jump ropes. Chapin says he’ll jam with the Cajuns and the Klezmatics but will leave the six-woman Divas squad to their own devices. “I wanted to sit in with them,” says the Brooklyn Heights–bred singer. “But it’s hard to sit when jumping rope. And being a folksinger, I don’t have much experience with divahood.”
9/10 from 1 to 6 p.m.; Robert F. Wagner Jr. Park, Battery Park City, access through Battery Pl. and the West Side Hwy. (212-267-9700 or bpcparks.org); free.