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 drag. It represents the theoretical maximum efficient speed for a displacement hull.

2. How Does the Calculator Work?

The calculator uses the hull speed formula:

Where:

• \( LWL \) — Waterline length 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 matches its length, causing increased resistance.

3. Importance of Hull Speed Calculation

Details: Knowing a boat's hull speed helps in voyage planning, fuel efficiency calculations, and understanding performance limitations. Exceeding hull speed requires exponentially more power.

4. Using the Calculator

Tips: Enter the waterline length in feet (measure from bow to stern at the waterline). The value must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: Can boats exceed hull speed?
A: Yes, but it requires significantly more power. Planing hulls can exceed hull speed by rising up on top of the water rather than pushing through it.

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 with sufficient power.

Q3: How accurate is the 1.34 coefficient?
A: It's an average value. Actual values range from 1.1 to 1.5 depending on hull shape, with slender hulls having higher coefficients.

Q4: Why measure at waterline length?
A: The waterline length determines the wave pattern created by the boat's movement through water, which affects its speed potential.

Q5: How does load affect hull speed?
A: Increased load lengthens the waterline, potentially increasing hull speed, but also increases displacement and required power.