1. What is Boat Prop Pitch Calculation?

Definition: This calculator determines the ideal propeller pitch based on boat speed, engine RPM, and propeller slip.

Purpose: It helps boat owners and marine technicians select the proper propeller for optimal performance.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Pitch — Propeller pitch in inches
• S — Boat speed in miles per hour (mph)
• RPM — Engine revolutions per minute
• Slip — Propeller slip factor (decimal, typically 0.05-0.15)

Explanation: The formula calculates how far the boat would move forward with each propeller rotation if there were no slip, then adjusts for real-world slip conditions.

3. Importance of Proper Prop Pitch

Details: Correct propeller pitch ensures optimal engine performance, fuel efficiency, and prevents over-revving or under-powering your engine.

4. Using the Calculator

Tips: Enter your boat's speed at wide-open throttle (WOT), the engine RPM at that speed, and an estimated slip factor (default 0.10 or 10%).

5. Frequently Asked Questions (FAQ)

Q1: What is propeller slip?
A: Slip is the difference between theoretical and actual boat movement per prop rotation, caused by water resistance and other factors.

Q2: What's a typical slip factor?
A: Most boats have 5-15% slip (0.05-0.15). High-performance boats may be lower, while heavily loaded boats may be higher.

Q3: Why is 1056 used in the formula?
A: This constant converts mph to inches per minute (1 mph = 1056 inches per minute at the prop).

Q4: How do I measure my boat's speed and RPM?
A: Use a GPS for speed and the engine's tachometer for RPM at wide-open throttle in calm conditions.

Q5: What if my calculated pitch doesn't match available props?
A: Choose the closest available pitch, or consult a prop specialist about custom options or pitch adjustments.