Abstract: A turbine assembly and a system for extracting tidal energy are disclosed. The turbine assembly may include identical sections disposed in a stacked arrangement. Each section may be shaftless, energizable by a fluid flow to produce lift and is appropriately oriented at a phase shift to an adjacent section such that a relatively constant resultant torque output with small amplitude fluctuation is generated by rotation of the turbine assembly. The turbine assembly may be employed in conjunction with a velocity enhancing device having a housing with variable profile openings to enhance the torque output. The turbine assembly may further be employed in a floating barrage arrangement which is transportable.