1. What is Hull Speed?

Hull speed is the theoretical maximum speed that a displacement hull can achieve without planing. It represents the point where the wavelength of the boat's wake equals the waterline length, creating significant wave-making resistance.

2. How Does the Calculator Work?

The calculator uses the hull speed formula:

Where:

• \( V \) — Theoretical hull speed (knots)
• \( LWL \) — Waterline length (feet)
• 1.34 — Empirical coefficient for displacement hulls

Explanation: The formula calculates the speed at which the wavelength created by the boat matches its waterline length, creating maximum wave resistance.

3. Importance of Hull Speed Calculation

Details: Understanding hull speed helps sailors optimize performance, plan passages, and set realistic speed expectations. It's crucial for sailboat design and performance analysis.

4. Using the Calculator

Tips: Enter the waterline length in feet. The value must be greater than zero. The calculator will provide the theoretical maximum hull speed in knots.

5. Frequently Asked Questions (FAQ)

Q1: Can boats exceed their hull speed?
A: Yes, modern designs with fine entries and powerful rigs can exceed hull speed through surfing or planing, but it requires significant additional power.

Q2: Does hull shape affect the 1.34 coefficient?
A: Yes, finer hulls might have slightly higher coefficients (up to 1.5), while fuller hulls might have lower values. 1.34 is a standard average.

Q3: How accurate is this calculation?
A: It provides a good theoretical estimate for traditional displacement hulls. Actual performance depends on hull shape, sail area, sea conditions, and crew skill.

Q4: Does this apply to powerboats?
A: Only to displacement powerboats. Planing powerboats operate differently and can far exceed their theoretical hull speed.

Q5: Why use waterline length instead of overall length?
A: Waterline length determines the wavelength the hull creates, which is what limits speed in displacement mode.