Abstract: The invention relates to a drive device for a surfboard, comprising movable elements for increasing the propulsion resulting from said drive device. Said elements are set in motion by the user of the surfboard. The user can thus travel through the water with their surfboard while simultaneously training their body.

Abstract: A paddle wheel rotatable about an axis and exposed to radial inward and crosswise water flow has a hub on the axis and about which the wheel is rotated in a rotation direction about the axis and a plurality of angularly spaced blades spaced radially outward from the hub, forming spaces through which water can flow, and each formed by a plurality of radially spaced arcuate elements each in turn having a radially outer end and a radially inner end. These elements are each concave between the respective ends toward the incoming water flow with the radial outer ends more widely spaced than radial inner ends such that each element forms an acute angle with the adjacent element or elements and the spaces between the blades narrow in a direction of flow of water through them.

Abstract: The invention relates to a water wheel, preferably an undershot or breast-shot water wheel having a horizontal hub (21), wherein paddle arrangements (15) are provided along the wheel circumference (22) for converting the kinetic and optionally also potential energy of the water stream into a rotational motion of the water wheel, wherein the paddle arrangements (15) comprise at least two paddle blades and the paddle blades have different sizes, characterized in that the outer paddle blade (13) has a greater depth (23) than the further inner paddle blades (14, 16, 17) of the paddle arrangement. The invention further relates to a hydroelectric power plant comprising one or a plurality of such water wheels.

Abstract: Blade for an impeller wheel which is suitable for use for an impeller wheel power station. The special design of the blade ensures relatively low swirling of the water flow behind the blade and increases the utilization of the inflowing water flow as a result.