A buoy connected to a fluid-flow machine with attached generator is specified in which the generator is driven according to the invention via an impeller turbine with pivotable turbine vanes. The pivoting of the turbine vanes and the adjustment of the setting angle is effected via sliding-link kinematics arranged in the hollow impeller. The impeller turbine, the disc-shaped impeller of which runs inside a conical ring at the bottom of the cylindrical body, is mounted well above the water surface via a supporting spindle in the cylindrical body of the buoy. The buoy equipped with the impeller turbine is supplied with sufficient energy even in unfavourable flow conditions and depths of water. On account of the proposed design, damage caused by flotsam or faults in the bearing arrangement of the rotatable parts need not be feared. The maintenance costs are low. <IMAGE>
