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Hull Speed Formula:
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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 waterline length, creating significant wave-making resistance.
The calculator uses the hull speed formula:
Where:
Explanation: The formula is derived from wave theory, where the speed of a wave is proportional to the square root of its wavelength. For boats, the wavelength is approximately equal to the waterline length.
Details: Understanding hull speed is crucial for sailboat design, performance prediction, and efficient sailing. It helps sailors determine the maximum efficient speed their boat can achieve under sail power alone.
Tips: Enter the waterline length in feet. The value must be greater than zero. The calculator will compute the theoretical hull speed in knots.
Q1: Can boats exceed their hull speed?
A: Yes, modern hull designs and planing hulls can exceed theoretical hull speed, but displacement hulls experience dramatically increased resistance near this speed.
Q2: How accurate is the 1.34 coefficient?
A: The coefficient can vary from 1.1 to 1.5 depending on hull form, but 1.34 is the standard value used for most displacement hull calculations.
Q3: Does hull speed apply to powerboats?
A: It primarily applies to displacement hulls. Planing hulls and semi-displacement hulls can exceed this speed with sufficient power.
Q4: How does waterline length affect hull speed?
A: Longer waterline length results in higher hull speed. Doubling the waterline length increases hull speed by approximately 41%.
Q5: Are there limitations to this formula?
A: The formula assumes ideal conditions and doesn't account for hull shape, weight distribution, or sea state. It's a theoretical maximum rather than a guaranteed speed.