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's a theoretical maximum for displacement hulls under normal conditions.

2. How Does the Calculator Work?

The calculator uses the hull speed formula:

Where:

• \( LWL \) — Load waterline length in meters
• 2.43 — Empirical coefficient for UK calculations

Explanation: The formula calculates the speed in knots where the wave-making resistance increases dramatically for displacement hulls.

3. Importance of Hull Speed Calculation

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

4. Using the Calculator

Tips: Enter the vessel's load waterline length (LWL) in meters. The value must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: Why is the coefficient 2.43 for UK calculations?
A: The UK formula uses imperial measurements converted to metric, resulting in a slightly different coefficient than the standard 1.34 used in some other systems.

Q2: 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.

Q3: How is LWL measured?
A: Load waterline length is the length of the hull at the waterline when normally loaded, measured from bow to stern along the waterline.

Q4: Does hull speed apply to all boats?
A: Primarily applies to displacement hulls. Semi-displacement and planing hulls can exceed this speed with sufficient power.

Q5: Why does hull speed matter for sailboats?
A: Sailboats typically can't generate enough power to exceed hull speed, making it an important performance limit.