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Shaft Sizing Calculator

Calculate propeller shaft diameter for your boat's drivetrain

Quick Samples
Try these common configurations to get started

Small Sailboat Auxiliary

Low power, high gear reduction

Mid-size Powerboat

Common planing hull setup

High-Performance Diesel

High torque, high strength material

Hull Dimensions
Enter your boat's principal dimensions
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About This Tool
This calculator determines the minimum required diameter of a solid propeller shaft based on the torque from the engine, the material's strength, and a desired safety factor. It's a critical calculation for ensuring the reliability of your boat's drivetrain.

Key Concepts:

Torque: The twisting force the engine applies to the shaft.
Yield Strength: The stress at which a material begins to permanently deform.
Safety Factor: How much stronger the shaft is than it needs to be.
Standard Sizes: Shafts are made in standard increments (e.g., 1/8").
Frequently Asked Questions

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