An apparatus for anchoring a floating off-shore unit or other type of floating vessel, comprising a rotatably mounted chain sprocket wheel (3) having a chain (3a) secured on its outer periphery, The wheel (3) being arranged to be rotated by reciprocating movement of at least two hydraulic cylinders (1, 2). Each of the cylinders (1, 2) is provided with a locking arm (6, 7) for releasably and mechanically engaging a portion of the wheel (3) in order to rotate the wheel (3) during movement of the respective cylinders (1, 2). Also described is a chain stopper comprising at least four blocks (8) that are hinged at their first ends and at their second ends have a surface that is adapted to engage a chain link The blocks (8) are mounted in opposite pairs.