Boat Max Speed Calculator

Hull Speed Formula:

\[ Max Speed = 1.34 \times \sqrt{LWL} \]

Max Speed:

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1. What is Hull Speed?

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

2. How Does the Calculator Work?

The calculator uses the hull speed formula:

\[ Max Speed = 1.34 \times \sqrt{LWL} \]

Where:

\( Max Speed \) — Maximum speed in knots
\( LWL \) — Load Waterline Length in feet
\( 1.34 \) — Empirical coefficient for hull speed

Explanation: The formula calculates the speed at which a displacement hull creates a wave pattern that matches its waterline length, beyond which resistance increases dramatically.

3. Importance of Hull Speed Calculation

Details: Understanding hull speed is crucial for boat design, performance prediction, fuel efficiency planning, and setting realistic expectations for vessel performance under power or sail.

4. Using the Calculator

Tips: Enter the Load Waterline Length (LWL) in feet. This is the length of the boat at the waterline when normally loaded. The value must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the 1.34 coefficient based on?
A: The coefficient 1.34 is derived from wave mechanics and represents the speed-length ratio where wave-making resistance becomes significant for displacement hulls.

Q2: Can boats exceed hull speed?
A: Yes, planing hulls and semi-displacement hulls can exceed hull speed with sufficient power. Displacement hulls require exponentially more power to exceed this speed.

Q3: How accurate is this calculation?
A: It provides a good theoretical maximum for displacement hulls. Actual performance may vary based on hull shape, weight distribution, and sea conditions.

Q4: Does this apply to all boat types?
A: Primarily for displacement hulls. Planing hulls, multihulls, and high-speed vessels operate on different principles and can exceed this speed more easily.

Q5: What factors affect actual boat speed?
A: Hull design, weight, power, propeller efficiency, sea state, wind, and current all influence actual speed performance beyond the theoretical hull speed.