The Hudson River sloop Clearwater has been spending some time tied up at the 79th Street Boat Basin’s A Dock in between some public sails the group has been running out of Dyckman Street Marina further north. The relatively recently rebuilt A Dock remains accessible even as the rest of the Boat Basin Marina is off limits. Clearwater used to base itself at A Dock when in New York City but cannot run programming from here with the marina closed. Clearwater is flying a Mexican flag off its mast, presumably in recognition of last week’s East River tragedy.