1. What is Hull Speed?

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 hull speed formula:

Where:

• \( LWL_{ft} \) — Waterline length in feet
• 1.34 — Empirical coefficient for displacement hulls

Explanation: The formula calculates the speed at which the wavelength of the boat's wake equals the boat's waterline length, creating increased drag.

3. Importance of Hull Speed Calculation

Details: Knowing a boat's hull speed helps in understanding its performance limitations, fuel efficiency, and sailing characteristics. Exceeding hull speed requires significantly 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.

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 the water surface.

Q2: How accurate is this formula?
A: It provides a good estimate for traditional displacement hulls but may be less accurate for modern hull designs.

Q3: Does hull shape affect hull speed?
A: While the basic formula uses length, hull shape can influence how close a boat can get to its theoretical hull speed.

Q4: What's the coefficient for multihulls?
A: Catamarans and trimarans often use a coefficient of 2.0-2.5 instead of 1.34 due to their reduced wave-making resistance.

Q5: How does load affect hull speed?
A: Increased load lengthens the waterline, potentially increasing hull speed, but also increases drag which may offset any gains.