The invention relates to an installation comprising windmills (
) which are mounted in a frame (
5, 6, 7
) said frame is provided with float bodies (
), and it is capable of rotation about a vertical axis in order to turn the windmills towards the wind. In order to keep the windmills upright, supporting means, for example a body (
) which is anchored to the bottom, are disposed some distance away from the plane of the windmills. Furthermore, means are provided for improving or simplifying maintenance.