1. What is Hull Speed?

Hull speed is the speed at which the wavelength of a vessel's bow wave equals the waterline length, creating increased resistance. It represents the theoretical maximum efficient speed for displacement hulls.

2. How Does the Calculator Work?

The calculator uses the hull speed formula:

Where:

• \( LWL \) — Length at waterline in feet
• 1.34 — Empirical coefficient for displacement hulls

Explanation: The formula calculates the speed (in knots) at which a displacement hull creates a wave system that limits its speed potential.

3. Importance of Hull Speed Calculation

Details: Knowing your vessel's hull speed helps in voyage planning, fuel efficiency calculations, and understanding performance limitations.

4. Using the Calculator

Tips: Enter the vessel's length at waterline in feet. The value must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: Can boats exceed hull speed?
A: Displacement hulls can exceed hull speed but with exponentially increasing power requirements. Planing hulls can exceed it by rising over their bow wave.

Q2: Does hull speed apply to all boats?
A: No, it primarily applies to displacement hulls. Planing hulls and semi-displacement hulls can exceed this speed.

Q3: How accurate is the 1.34 coefficient?
A: It's an average. Actual values range from 1.1 to 1.5 depending on hull shape and other factors.

Q4: What if I only know overall length?
A: For most monohulls, LWL is about 90% of LOA. For precise calculations, use actual waterline length.

Q5: Does hull speed change with load?
A: Yes, as loading affects waterline length. A heavily loaded boat may have a longer waterline and thus higher hull speed.