NOVELTY - A hydro power system (1) has preferably positively buoyant vanes (19) pivotally mounted in pairs of in uniformly distributed sets on an endless conveyor (11). The vanes and conveyor in combination have neutral buoyancy. The conveyor is supported by one or two pylons (3,5) offset from one another in direction of a local current. One vane in each pair may lie on one side of the conveyor, while the other vane may lie on the opposite side of the conveyor.    USE - Hydro power system for electricity generation. Can also be used in flow of water e.g. river, tide way, estuary, as well as in sea bed, river bed, fast-current river valley, gorge, or canyon.    ADVANTAGE - The neutral buoyancy of the vanes as well as the endless conveyor reduces operational loads applied to the system. Transverse loads applied to the system may be reduced since the vanes and the endless conveyor may be effectively self-supporting. The vanes may be positively buoyant to at least partly offset the weight of the conveyor and achieve the neutral buoyancy. Locking device retains vanes in the contracted position to facilitate servicing and or maintenance. Vanes may be shaped to present streamlined profile when in contracted position or to pivot between extended and retracted positions in response to local flow conditions. Set of three vanes may define angular displacement of 120 degrees between vanes so as to ensure axial loading on conveyor and reduce turning or twisting moments applied to conveyor. System can be mounted on e.g. fast-current river valley, gorge, canyon, using overspill or perforated dams that deepen water without reducing aggregate power current. Gated sluices are provided on dam or upstream of system to facilitate water level control. Upstream sluices may be provided with gates or valves and piped or formed with canals to discharge below dam so as to dry out system for maintenance or alterations. Screens of metal, plastic, or textile nets are attached to anchor cables of beacon buoys or to similar beacon pylons surrounding installation to protect large marine creatures as well as system from damage from such creatures. Conveyor may be located far below surface so as not present danger to normal shipping any may be used with warnings for fishing lines and trawls.    DESCRIPTION OF DRAWING(S) - The drawing shows the side view of a hydro power system.    Hydro power system (1)    Pylons (3,5)    Endless conveyor (11)    Drive wheels (13,15)    Vanes (19)