Boat Speed Calculator
Estimate boat speed using Crouch's formula based on engine power, displacement, and hull type.
Input Parameters
Enter details for calculation.
Estimated Speed
Expert Tip
Crouch's constant varies from 150 (displacement hulls) up to 250+ (high-speed planing racing hulls).
Calculation Methodology & Details
Formula
Applies Crouch's empirical formula for planing and semi-displacement boats.
Important Disclaimer
The calculations provided are for educational and general informational purposes only. They do not replace professional advice or diagnostic validation. Always consult a qualified specialist.
How Boat Speed is Estimated
Follow these steps to complete the calculation:
Input Power
Enter net horsepower delivered to the propeller shaft.
Input Displacement
Enter total vessel weight including fuel, gear, and crew.
Related Tools
Detailed Insights & Expert Guide
ℹ️ About this Calculation
Boat speed estimation helps marine engineers and boating enthusiasts estimate the maximum theoretical speed of a displacement or planing hull. It commonly employs Crouch's Formula, an empirical method relating propeller shaft horsepower, displacement, and a hull-specific design constant.
Variable Glossary
Shaft Power
The horsepower delivered directly to the boat's propeller shaft.
Displacement
The total weight of the water displaced by the boat, equivalent to the boat's weight in pounds.
Hull Constant
A constant based on hull design, ranging from 150 for heavy displacement boats to over 250 for racing hulls.
How to Calculate Step-by-Step
Step 1
Enter the engine shaft horsepower (HP) and total vessel displacement weight (lbs).
Step 2
Determine your hull constant based on boat type (e.g., utility planing boats usually average 180-200).
Step 3
Divide horsepower by displacement weight and take the square root of the result.
Step 4
Multiply by the hull constant to obtain the estimated speed in knots.