1. What is Hull Speed?

Hull speed is the speed at which the wavelength of a vessel's bow wave equals the waterline length, creating maximum wave resistance. It's the theoretical maximum speed a displacement hull can achieve without planing.

2. How Does the Calculator Work?

The calculator uses the Hull Speed formula:

Where:

• \( LWL \) — Waterline length in feet
• 1.34 — Empirical coefficient for displacement hulls

Explanation: The formula shows that hull speed increases with the square root of the waterline length. The coefficient 1.34 is derived from wave-making resistance theory.

3. Importance of Hull Speed Calculation

Details: Knowing a boat's hull speed helps in performance prediction, fuel efficiency planning, and understanding the practical speed limits of displacement hull vessels.

4. Using the Calculator

Tips: Enter the waterline length in feet. This is the length of the boat at the water's surface from bow to stern. The value must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: Can boats exceed hull speed?
A: Displacement hulls cannot efficiently exceed hull speed without planing. Semi-displacement or planing hulls can exceed it with sufficient power.

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

Q3: Does hull shape affect hull speed?
A: The formula assumes a typical displacement hull. Extreme hull shapes may have slightly different performance characteristics.

Q4: What about metric units?
A: The formula is designed for feet. For meters, use 2.43 × √LWL (meters) instead.

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