You came after a boat spin and noticed an out-of-control tachometer. It sounds like the propeller s hub insert has slipped. The hub is an essential piece on your boat prop designed to break if something hits the propeller. It s a great safety feature to protect more expensive boat parts from breaking. It s a sacrificial piece. When it is done with its purpose, you just have to replace it. Consider adding a spare of this XHS 20-70 HP Delrin Hub Insert (991501) on your boat kit then you know you have it when needed. Or perhaps think about always carrying a spare prop too. Apart from this, it s crucial to bring the standard tools on board so you ll enjoy an anxious-free journey onshore. Key Features: Shock absorber, designed to break and shear when something hits the boat prop Save cost by protecting more expensive boat parts in case of shock High-Quality Product Specifications: SKU: 991501 UPC: 014984026260