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. It represents the theoretical maximum speed a displacement hull can achieve without planing.

2. How Does the Calculator Work?

The calculator uses the hull speed equation:

Where:

• \( LWL \) — Waterline length (feet)
• \( age\_factor \) — Adjustment for boat age (0.7-1.0)
• 1.34 — Empirical hull speed coefficient

Explanation: The equation accounts for the relationship between waterline length and wave-making resistance, with an adjustment factor for boat age.

3. Importance of Hull Speed Calculation

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

4. Using the Calculator

Tips: Enter waterline length in feet and boat age in years. The age factor accounts for hull fouling and wear over time.

5. Frequently Asked Questions (FAQ)

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

Q2: How does age affect hull speed?
A: Older boats may have hull fouling, increased weight, or hull deformation that reduces efficiency, hence the age factor.

Q3: What's a typical hull speed for sailboats?
A: Most cruising sailboats have hull speeds between 5-8 knots depending on size.

Q4: Does hull shape affect the calculation?
A: The basic formula assumes traditional displacement hulls. Extreme hull designs may vary.

Q5: How accurate is this calculation?
A: It provides a theoretical maximum. Actual speed depends on many factors including hull condition, load, and sea state.