1. What is Prop Slippage?

Prop slippage is the difference between the theoretical speed a propeller should produce (based on its pitch and RPM) and the actual speed achieved. It's expressed as a percentage and indicates the efficiency of the propeller.

2. How Does the Calculator Work?

The calculator uses the prop slippage formula:

Where:

• Theoretical Speed — Speed the propeller should produce (m/s)
• Actual Speed — Measured speed of the vessel (m/s)

Explanation: The formula calculates what percentage of the theoretical speed is lost due to slippage.

3. Importance of Slippage Calculation

Details: Measuring prop slippage helps evaluate propeller efficiency, diagnose propulsion system issues, and optimize performance. Lower slippage means better efficiency.

4. Using the Calculator

Tips: Enter both theoretical and actual speeds in meters per second (m/s). Theoretical speed should be greater than actual speed for meaningful results.

5. Frequently Asked Questions (FAQ)

Q1: What is a good slippage percentage?
A: Typically 5-25% for most vessels. High-performance boats may have 5-15%, while displacement hulls may have 15-25%.

Q2: What causes high prop slippage?
A: Causes include incorrect propeller size, hull fouling, excessive weight, or poor hull design.

Q3: Can slippage be negative?
A: Normally no. If actual speed exceeds theoretical, check your measurements or calculations.

Q4: How does slippage affect fuel efficiency?
A: Higher slippage generally means lower fuel efficiency as more energy is wasted.

Q5: How can I reduce prop slippage?
A: Proper propeller selection, maintaining clean hull, and optimal weight distribution can help reduce slippage.