A wind-energy-power-generating device is disclosed for flotation on a body of water. The device includes a turbine assembly having rotor blades rotating about a rotation axis for harnessing kinetic energy from an airflow. The device includes a cowl at least partially surrounding said turbine assembly and defining an airflow passageway between a cowl inlet and outlet, having an inlet and outlet axis, respectively. The inlet and outlet axis intersect at a redirect angle. The device includes a base platform adapted to support the turbine assembly and cowl on the water. The cowl is rotatably mounted on the base platform such that it is rotatable around the turbine assembly to self-align with a wind direction. Stabilising arms extend from the base platform and are spaced circumferentially around a platform axis, to stabilise it on the water. A wind-energy-power-generating device secured to the ground or other fixed non-floating structure is also described.