1. What is a Boat Top Speed Calculator?

Definition: This calculator estimates a boat's maximum speed based on engine power, boat displacement, and hull characteristics.

Purpose: It helps boat owners, designers, and marine enthusiasts predict theoretical top speed before sea trials.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( S \) — Boat speed (knots or mph)
• \( C \) — Hull speed constant (unitless)
• \( P \) — Engine power (horsepower)
• \( D \) — Boat displacement (pounds)

Explanation: The formula shows that speed increases with power but decreases with the square root of displacement.

3. Importance of Speed Calculation

Details: Accurate speed estimation helps in engine selection, fuel planning, and performance optimization.

4. Using the Calculator

Tips: Enter the hull constant (default 1.34 for displacement hulls), engine horsepower, and boat displacement in pounds. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical hull speed constant?
A: About 1.34 for displacement hulls, 1.1-1.3 for semi-displacement, and higher for planing hulls.

Q2: Should I use knots or mph?
A: The formula works for both - just be consistent. 1 knot = 1.15078 mph.

Q3: What affects the hull speed constant?
A: Hull shape, length-to-beam ratio, and whether the boat planes or displaces water.

Q4: How do I find my boat's displacement?
A: Check manufacturer specs or calculate from hull volume and material density.

Q5: Why doesn't my actual speed match the calculation?
A: Real-world factors like hull fouling, sea conditions, and propeller efficiency affect actual speed.