River hydrokinetic turbines harness renewable energy in river currents to contribute to microgrids. Despite many hydrokinetic turbine designs, systems still require reducing costs and operate effectively in cold climates. A stable-wing-support system is developed and tested to deploy, retrieve, and operate within the water column of a horizontal axis river turbine. The prototype design addresses identified stability problems using a fixed-wing design previously tested in a laboratory water tunnel and an energetic river. The stable-wing-support system prototype uses a NACA 0012 airfoil with 6°, 10°, and 15° dihedral angles designed using open-source Xflr5 software to optimize the lift, drag, and moment coefficients for angles of attack from -5° to +15°. The prototype also includes a winged tail to improve the turbine assembly's stability further. The stable-wing-support prototype designed using SolidWorks is 3-D printed. Tests are conducted to quantify the stability of the stable-wing-support prototype using a water tunnel at flow velocities varying from 0.5 to 1 m/s, resulting in Reynold’s numbers from 3.37x105 to 6.74x105. Stability data is recorded and analyzed using open-source Tracker software and then exported to MATLAB software for analysis. Results indicate that the stability of the stable-wing-support system with dihedral angles 6°, 10°, and 15° and a winged tail significantly improves the stability by 80%, 50%, and 40%, respectively, compared to a previous design for flow velocities up to 1 m/s, addressing the objectives of this research and contribute a design to maximizing power production in cold climates.