Mercury - Quicksilver Thunderbolt Propeller High-Performance Prop Series High-Polished Stainless Steel QS5008X. Overview. There's a moment when you ease the throttle forward and the boat just settles into its stride. No drama. No hesitation. Just clean power translating straight into motion. That's what the Quicksilver Thunderbolt propeller is built for. It's a prop you trust when you're running long distances, carrying real load, or leaning on serious horsepower, because it feels planted and pr