Hull Speed Formula:
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Definition: This calculator estimates the theoretical maximum speed (hull speed) that a displacement hull power boat can achieve without planing.
Purpose: It helps boat owners, designers, and marine enthusiasts understand the performance limitations of displacement hull vessels.
The calculator uses the formula:
Where:
Explanation: The formula calculates the speed at which the boat's bow and stern waves synchronize, creating maximum wave resistance.
Details: Understanding hull speed helps in boat design, engine selection, and fuel efficiency planning. Exceeding hull speed requires significantly more power.
Tips: Enter the boat's waterline length in feet (measured from bow to stern at the waterline). The value must be > 0.
Q1: Does this apply to all boats?
A: No, this only applies to displacement hulls. Planing hulls can exceed this speed with sufficient power.
Q2: Why is the constant 1.34 used?
A: This empirical constant accounts for the relationship between wave-making resistance and hull length in salt water.
Q3: How does waterline length affect speed?
A: Longer waterline lengths generally allow for higher hull speeds, following the square root relationship.
Q4: Is this accurate for multihulls?
A: Multihulls often exceed this speed due to their narrow hulls, using a higher constant (typically 1.8-2.5).
Q5: How does hull shape affect actual speed?
A: While this gives theoretical maximum, actual speed depends on hull efficiency, power, and sea conditions.