Propeller Shaft Torque Calc

Marine Shaft Size & Speed

$1.99 · Designed for iPad. Not verified for macOS.

Repowering to 350HP at 2,200 shaft RPM - will a 1.5-inch shaft hold? Required diameter, torsional stress, critical speed for SS and Monel. $1.99 one-time, no login. Repowering your boat and need to know if the existing shaft can handle more torque? Enter engine HP, RPM, and gear ratio to get required shaft diameter, torsional stress, and critical speed margin — so you avoid a broken shaft at sea. TORQUE CALCULATOR Enter engine horsepower, shaft RPM, and safety factor. Calculates required shaft torque, minimum shaft diameter, and torsional stress. Supports multiple shaft materials. SHAFT SIZE TABLE Reference table of common shaft diameters (3/4 to 4 inches) with maximum torque capacity for stainless steel and Monel. Includes recommended RPM ranges for each size. MATERIAL COMPARISON Compare marine shaft materials: 316 Stainless, Monel K-500, Aquamet 17, and Aquamet 22. Shows yield strength, fatigue limit, corrosion resistance, and typical applications side by side. CRITICAL SPEED Calculate critical shaft speed based on shaft length, diameter, and bearing spacing. Shows safety margin above operating RPM to avoid vibration resonance. Built for marine engineers, boat builders, and propulsion system designers. Works offline.

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Added a More Pro Tools section to discover related field calculators.

Version 1.0.2

The developer, Shanghai Sheyuan Network Technology Co., Ltd., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

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    Information

    Seller
    • Shanghai Sheyuan Network Technology Co., Ltd.
    Size
    • 1.1 MB
    Category
    • Utilities
    Compatibility
    Requires iOS 17.0 or later.
    • iPhone
      Requires iOS 17.0 or later.
    • iPad
      Requires iPadOS 17.0 or later.
    • Mac
      Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    • English
    Age Rating
    4+
    Copyright
    • © 2026 Sheyuan Inc.
  • Developer Website
  • Privacy Policy

    • Supports

    • Family Sharing

      Up to six family members can use this app with Family Sharing enabled.

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