1. What is a Hull Speed Calculator?

Definition: This calculator estimates the theoretical maximum speed a displacement hull can achieve without planing.

Purpose: It helps boat designers, sailors, and marine enthusiasts understand a vessel's speed potential based on its waterline length.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( HS \) — Hull speed (knots)
• \( LWL \) — Waterline length (feet)
• 1.34 — Empirical constant 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 maximum wave resistance.

3. Importance of Hull Speed Calculation

Details: Understanding hull speed helps in boat design, fuel efficiency planning, and setting realistic performance expectations.

4. Using the Calculator

Tips: Enter the boat's waterline length in feet (measured from bow to stern at the water's surface). The value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is waterline length (LWL)?
A: The length of the boat where it meets the water surface, which may differ from the overall length.

Q2: Why 1.34 as the constant?
A: This empirical value accounts for the relationship between wave-making resistance and hull length in displacement vessels.

Q3: Can boats exceed hull speed?
A: Yes, with sufficient power, planing hulls can exceed this speed, but displacement hulls face dramatically increased resistance.

Q4: Does this apply to all boat types?
A: No, it's primarily for displacement hulls. Planing hulls and multihulls have different speed characteristics.

Q5: How does hull shape affect the calculation?
A: While the formula is length-based, hull shape affects how close to theoretical hull speed a boat can practically achieve.