1. What is a Boat Speed Calculator Prop?

Definition: This calculator estimates boat speed based on engine RPM, propeller pitch, and propeller slip factor.

Purpose: It helps boaters and marine engineers predict theoretical boat speed for propeller selection and performance analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Boat speed (knots)
• \( RPM \) — Engine revolutions per minute
• \( PP \) — Propeller pitch (inches)
• \( Slip \) — Propeller slip factor (0-1)
• 1215.1 — Conversion factor (inches to nautical miles per hour)

Explanation: The formula calculates theoretical speed then accounts for propeller slip (typically 10-20% for most boats).

3. Importance of Boat Speed Calculation

Details: Accurate speed prediction helps with fuel planning, propeller selection, and performance optimization.

4. Using the Calculator

Tips: Enter engine RPM, propeller pitch in inches, and slip factor (default 0.12 for 12% slip). All values must be valid (RPM > 0, pitch > 0, 0 ≤ slip < 1).

5. Frequently Asked Questions (FAQ)

Q1: What is propeller slip?
A: Slip is the difference between theoretical and actual speed caused by water "slipping" past the propeller blades.

Q2: What's a typical slip factor?
A: Most boats have 10-20% slip (0.10-0.20). High-performance boats may have less, while heavily loaded boats may have more.

Q3: How do I find my propeller pitch?
A: The pitch is usually stamped on the propeller hub or in your boat's specifications.

Q4: Why is the result in knots?
A: Knots (nautical miles per hour) is the standard speed unit in marine applications.

Q5: Does this account for hull drag or load?
A: No, this is theoretical speed. Actual speed may vary based on hull design, load, and sea conditions.