Abstract: There is described a marine turbine assembly comprising a frame having a receiving surface and a front end; at least one turbine mounted to the receiving surface of the frame and comprising a rotor and a plurality of blades projecting therefrom, the rotor being operatively connectable to an electrical generator for generating electrical energy from a water current. A ballast system is coupled to the frame and balancedly distributed around a perimeter thereof. The ballast system has at least one compartment with at least one aperture for selectively receiving and selectively expelling pressurized fluid from a source of pressurized fluid, thereby controlling at least one of a trim and a buoyancy of the marine turbine assembly.