1. What is Displacement Hull Speed?

The displacement hull speed is the theoretical maximum speed a displacement hull can achieve without planing. It's determined by the waterline length of the vessel and represents the point where the wavelength of the boat's wake equals the waterline length.

2. How Does the Calculator Work?

The calculator uses the displacement hull speed formula:

Where:

• \( Speed \) — Hull speed in knots
• \( Waterline\ Length \) — Length of the vessel at the waterline in feet
• 1.34 — Empirical coefficient for displacement hulls

Explanation: The formula is derived from wave-making resistance theory, where the speed of a wave is proportional to the square root of its wavelength.

3. Importance of Hull Speed Calculation

Details: Knowing a vessel's hull speed helps in design, performance prediction, and fuel efficiency planning. Exceeding hull speed requires exponentially more power.

4. Using the Calculator

Tips: Enter the waterline length in feet. The value must be greater than zero. The result is the theoretical maximum speed in knots for a displacement hull.

5. Frequently Asked Questions (FAQ)

Q1: Can boats exceed hull speed?
A: Yes, but it requires transitioning to planing mode (for planing hulls) or significant power (for semi-displacement hulls).

Q2: Does hull speed apply to all boat types?
A: No, it specifically applies to displacement hulls. Planing hulls can exceed this speed.

Q3: How accurate is the 1.34 coefficient?
A: It's an average value. Some boats may have coefficients between 1.1 to 1.5 depending on hull shape.

Q4: Why does waterline length matter more than overall length?
A: Because it's the actual length interacting with the water and creating the wave system that determines resistance.

Q5: How does hull speed relate to fuel efficiency?
A: Operating near hull speed is typically most efficient for displacement hulls. Exceeding it dramatically increases fuel consumption.