Abstract: A fluid foil for use in a marine propeller having an upper surface with a uniform, continuous convex shape commencing at the leading edge and terminating at the trailing edge of the foil section and a lower foil face having a convex shape extending from the said leading edge to the foil mid/chord position and having a concave shape extending from the said mid-chord position to the said trailing edge. An effective pitch line extending from the foil leading edge to the foil trailing edge is intersected tangentially by the concave shape of the lower foil face.

Abstract: A fishway comprising a channel having spaced-apart side walls and an interconnecting bottom wall for conducting a flow of water therethrough, a plurality of longitudinally spaced vortex generators formed on each channel side wall for providing reversing vortices in the flow stream of water along the channel whereby alternately reversing cross-stream water flows and upstream water flows are created to assist fish using the fishway in upstream travel. The vortex generators are provided by uniformly spaced baffles extending alternately from the channel side walls. The channel can be straight or curved in the form, for example, of a helix.