1. What is the Boat Speed Formula?

The boat speed formula calculates theoretical boat speed based on propeller RPM and pitch. This provides an estimate of how fast your boat should be moving through the water under ideal conditions.

2. How Does the Calculator Work?

The calculator uses the boat speed formula:

Where:

• \( RPM \) — Engine/propeller revolutions per minute
• \( Pitch \) — Propeller pitch in inches (theoretical forward movement per revolution)
• 1056 — Conversion factor accounting for units and slip

Explanation: The formula calculates theoretical speed before accounting for real-world factors like slip, hull drag, and water conditions.

3. Importance of Boat Speed Calculation

Details: Understanding your boat's theoretical speed helps with propeller selection, engine tuning, and performance expectations. It's a baseline for comparing actual performance.

4. Using the Calculator

Tips: Enter accurate RPM and pitch values. RPM should be measured at wide-open throttle. Pitch is typically marked on the propeller.

5. Frequently Asked Questions (FAQ)

Q1: Why is actual speed often lower than calculated?
A: Propeller slip (typically 10-20%), hull drag, water conditions, and load all reduce actual speed below theoretical.

Q2: How do I measure propeller pitch?
A: Pitch is usually stamped on the propeller hub. It represents the theoretical forward movement (in inches) per revolution.

Q3: What's a good speed range for my boat?
A: This depends on boat type. Displacement hulls are limited to hull speed, while planing hulls can exceed this with sufficient power.

Q4: How does propeller diameter affect speed?
A: While not in this formula, diameter affects thrust and efficiency. The right diameter is crucial for proper engine loading.

Q5: Can I use this for any boat type?
A: This works best for standard propeller-driven boats. Special cases (jets, surface-piercing props, etc.) need different calculations.