KINGSTON, N.Y. — Folk legend Pete Seeger helped dream up the sloop Clearwater in the 1960s as symbol of efforts to rid pollution from the Hudson River. Now, the river is cleaner and the old boat needs restoring.

Workers this winter are stripping planks off the hull of the 106-foot sloop and replacing parts of its frame for a massive overhaul for the Clearwater. And while the $850,000 price tag is putting a strain on the not-for-profit that runs the ship, it is still committed to the goal of getting the vessel back on the river by mid-June.

“I can’t imagine the Hudson River without the Clearwater sailing on it. It’s a really important part of Pete’s environmental legacy. It’s just not an option to fail getting this boat together,” said Dave Conover, newly appointed interim executive director of the sloop’s eponymous parent organization.

Seeger, who died in 2014 at age 94, lived on a bluff overlooking the river. Back in the ’60s, when the Hudson was notoriously fouled by sewage and factory waste, he promoted the idea of building a boat to get people to “learn to love their river again.” Organizers who held a naming contest rejected possibilities like Sojourner Truth and Sewer Rat for one evocative of its mission: Clearwater.

Forty-seven years after its christening, about 500,000 people have set foot on its decks, many children on class trips. Kids aboard the “sailing classroom” help steer with the tiller, test water quality and – in a nod to Seeger – sing old songs.

Robert F. Kennedy Jr., chief prosecuting attorney for Riverkeeper, said kids who rode Clearwater later became recruits for his environmental group. Kennedy said Seeger was a “pied piper” leading people back to the river and the sloop became critical to that mission.

“It would be like losing Grand Central Station. It’s part of this state,” Kennedy said. “People love looking out on the river and seeing the sloop.”

To keep the boat seaworthy, Clearwater has spent two previous winters replacing planks and parts of the frame below the water line. This winter, the middle section is being worked on by about 16 people on a barge docked just off the river in Kingston, about 80 miles north of New York City.

It’s costly work. Capt. Annika Savio estimates the lumber alone is about $130,000. Restoration costs played a role in the cancellation of the group’s popular Clearwater Hudson River Revival, a music festival held every summer at Croton-on-Hudson. The concerts evolved from “folk picnics” Seeger and his wife, Toshi, hosted in the 1960s to help pay for building the boat.