1. What is Hull Speed?

Hull speed is the speed at which the wavelength of a boat's bow wave equals the boat's 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:

• \( LWL \) — Load waterline length in feet
• 1.34 — Empirical constant for displacement hulls

Explanation: The formula calculates the speed at which the boat's wave system creates maximum resistance, making it inefficient to go faster without planing.

3. Importance of Hull Speed Calculation

Details: Knowing your boat's hull speed helps in voyage planning, fuel efficiency calculations, and understanding performance limitations of displacement hulls.

4. Using the Calculator

Tips: Enter the boat's waterline length in feet. This is typically slightly shorter than the boat's overall length. The value must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: Can boats exceed hull speed?
A: Yes, with sufficient power, planing hulls can exceed hull speed by rising over their bow wave, while semi-displacement hulls can exceed it by 10-20%.

Q2: Does hull speed apply to all boats?
A: No, it mainly applies to displacement hulls. Planing hulls (like speedboats) can far exceed hull speed when enough power is applied.

Q3: How accurate is this calculation?
A: It provides a theoretical maximum for displacement hulls. Actual maximum speed depends on hull shape, power, and sea conditions.

Q4: Why is the constant 1.34?
A: This empirical constant accounts for the relationship between wave-making resistance and waterline length in displacement hulls.

Q5: How does hull shape affect hull speed?
A: Finer hulls with less wetted surface can approach hull speed more efficiently, while fuller hulls may struggle to reach it.