BEACON — The sloop Clearwater is celebrating 50 years of sailing on the Hudson River.

Clearwater's founders and crew members will gather with public officials along the Hudson in Beacon on Friday to mark the anniversary of the sloop's launch on May 17, 1969.

They will hold an on-board christening ceremony.

Folk singer Pete Seeger and like-minded environmentalists wanted the ship to be a symbol of the river and a sort of floating classroom. It was built to look like the Dutch sloops that used to carry food and other supplies up and down the Hudson River.