1. What is Hull Speed?

Hull speed is the theoretical maximum speed a displacement hull can achieve without planing. It's determined by the waterline length of the vessel and represents the point where the vessel's bow wave length equals the waterline length.

2. How Does the Calculator Work?

The calculator uses the hull speed formula:

Where:

• \( Hull\_speed \) — Theoretical maximum speed in knots
• \( LWL \) — Waterline length in feet
• 1.34 — Empirical coefficient for displacement hulls

Explanation: The formula is derived from wave-making resistance physics, where speed is proportional to the square root of waterline length.

3. Importance of Hull Speed Calculation

Details: Knowing a vessel's hull speed helps in voyage planning, fuel efficiency optimization, and understanding performance limitations of displacement hulls.

4. Using the Calculator

Tips: Enter the vessel's waterline length in feet. The value must be greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: Can a boat exceed its hull speed?
A: Displacement hulls can exceed hull speed with sufficient power, but it becomes extremely inefficient. Planing hulls can exceed it by rising up on the water surface.

Q2: Does hull speed apply to all boats?
A: No, it only applies to displacement hulls. Planing hulls and semi-displacement hulls can exceed this theoretical limit.

Q3: How accurate is the 1.34 coefficient?
A: It's an average value. Actual values range from 1.1 to 1.5 depending on hull shape and other factors.

Q4: Why does waterline length affect speed?
A: Longer waterline creates longer waves, allowing higher speeds before wave-making resistance becomes prohibitive.

Q5: How does hull speed relate to fuel efficiency?
A: Fuel efficiency typically decreases dramatically as a vessel approaches and exceeds hull speed.