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Crouch's Formula:
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Crouch's formula is a mathematical equation used to estimate the speed of a boat based on its horsepower and displacement. It's widely used in marine engineering and boat design to predict performance characteristics.
The calculator uses Crouch's formula:
Where:
Explanation: The formula shows that boat speed is proportional to the square root of the power-to-weight ratio, with the Crouch constant accounting for hull efficiency.
Details: Accurate speed prediction helps in boat design, engine selection, performance optimization, and safety planning. It's essential for marine engineers, boat builders, and enthusiasts.
Tips: Enter horsepower in hp, displacement/weight in pounds, and select the appropriate Crouch constant based on your boat type. All values must be positive numbers.
Q1: What is the Crouch constant and how do I choose it?
A: The Crouch constant represents hull efficiency. Racing boats have higher constants (150-190), while cruisers have lower ones (210-230). Choose based on your boat type.
Q2: How accurate is Crouch's formula?
A: It provides good estimates for displacement and semi-displacement hulls. For planing hulls, it's reasonably accurate but may vary based on specific hull design.
Q3: Can I use this formula for all types of boats?
A: It works best for motorboats with conventional hull designs. It may be less accurate for sailboats, catamarans, or unusual hull forms.
Q4: What units should I use?
A: Horsepower in hp, weight in pounds, speed in knots. For metric units, convert accordingly (1 hp = 0.7457 kW, 1 lb = 0.4536 kg, 1 knot = 1.852 km/h).
Q5: Why does weight affect speed so significantly?
A: Weight directly impacts the power-to-weight ratio. Heavier boats require more power to achieve the same speed due to increased water resistance and displacement.