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Displacement Hull Speed Formula:
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The displacement hull speed formula calculates the theoretical maximum speed of a displacement hull vessel based on its waterline length. This formula is fundamental in naval architecture and sailing for predicting vessel performance.
The calculator uses the displacement hull speed formula:
Where:
Explanation: The formula is based on the relationship between wave-making resistance and hull length, where the speed increases with the square root of the waterline length.
Details: Understanding hull speed is crucial for vessel design, performance prediction, and efficient operation. It helps determine the practical speed limits for displacement hull vessels before wave resistance becomes excessive.
Tips: Enter the waterline length in feet. The value must be greater than zero. The calculator will provide the theoretical maximum speed in knots.
Q1: What is a displacement hull?
A: A displacement hull is a type of boat hull that moves through the water by pushing it aside (displacing it) rather than riding on top of it. Most sailboats and trawlers have displacement hulls.
Q2: Why does hull speed matter?
A: Hull speed represents the point where wave resistance increases dramatically. Exceeding this speed requires disproportionately more power and is generally inefficient for displacement hulls.
Q3: Can modern boats exceed hull speed?
A: Yes, planing hulls and semi-displacement hulls can exceed theoretical hull speed by generating lift, but pure displacement hulls are limited by this formula.
Q4: How accurate is the 1.34 coefficient?
A: The coefficient can vary from 1.1 to 1.5 depending on hull shape, but 1.34 is the standard value for typical displacement hulls.
Q5: Does hull speed apply to all vessels?
A: No, it primarily applies to displacement hull vessels. Planing hulls, hydrofoils, and other high-speed designs operate differently.