Mercury - Thunderbolt Propeller High-Performance Series High-Polished Stainless Steel QS5002X. Overview. There's a certain confidence that comes from knowing the prop under your boat is built to handle whatever the day throws at you. When you're running offshore before sunrise or trimming up for a fast run back to the marina, you want a propeller that feels steady, predictable, and strong. The Quicksilver Thunderbolt has that reassuring feel-the kind that tells you the power you're pushing is be