Mercury - Thunderbolt Propeller High-Performance Series High-Polished Stainless Steel QS5007X. Overview. There's a certain comfort that comes from knowing your boat will respond the moment you ask it to. It's that steady confidence you feel when the engines come alive, the hull lifts, and the propeller grabs hold of the water like it's meant to. The Thunderbolt propeller carries that feeling from the first throttle push to the last mile of the day. Whether you're running a big offshore spread or