1. What is Hull Speed?

Hull speed is the theoretical maximum speed that a displacement hull can efficiently travel through water. It's determined by the waterline length and hull type. Full displacement hulls have a lower hull speed than semi-displacement hulls.

2. How Does the Calculator Work?

The calculator uses the hull speed equation:

Where:

• \( LWL \) — Waterline length in feet
• \( hull\_type\_factor \) — 1.0 for full displacement hulls, 1.2 for semi-displacement hulls

Explanation: The equation accounts for the relationship between waterline length and wave-making resistance, with different factors for different hull types.

3. Importance of Hull Speed Calculation

Details: Knowing your vessel's hull speed helps in fuel efficiency planning and understanding performance limitations. Exceeding hull speed significantly increases fuel consumption.

4. Using the Calculator

Tips: Enter waterline length in feet and select your hull type. The calculator will estimate your vessel's theoretical maximum efficient speed.

5. Frequently Asked Questions (FAQ)

Q1: Why do semi-displacement hulls have a higher factor?
A: Semi-displacement hulls can partially plane, allowing them to exceed traditional hull speed more efficiently than full displacement hulls.

Q2: Can a boat exceed its hull speed?
A: Yes, but it requires significantly more power and fuel. Displacement hulls become very inefficient above hull speed.

Q3: How do I measure waterline length?
A: Measure the length of the boat at the waterline from bow to stern when the boat is normally loaded.

Q4: Does hull speed apply to planing hulls?
A: No, planing hulls are designed to rise up and ride on top of the water at higher speeds.

Q5: Why is the constant 1.34 used?
A: This empirical constant relates waterline length to wave-making resistance in displacement hulls.