Boat Resistance Calculation

Boat Resistance CalculationREF: EN-219-HYDRODYNAMICS

                Calculate the estimated total hydrodynamic resistance of your vessel as it moves through the water. By inputting your boat's waterline length, displacement weight, and target speed, this tool estimates the drag forces acting against the hull and determines the theoretical engine power required to overcome that resistance.
            
INPUT PARAMETERS
> SYS_UNIT:
                    
                    > WATERLINE_LENGTH [FT]
                    
                    > DISPLACEMENT_WEIGHT [LBS]
                    
                    > TARGET_SPEED [KNOTS]
                    
                    > HULL_TYPE_CONSTANT
                    
> OUTPUT_TOTAL_RESISTANCE

                0.00 LBS
            
                EST. POWER REQUIRED: 0.0 HP
            
Understanding Boat Resistance
                When a vessel moves through water, it experiences drag. Overcoming this drag requires mechanical power. In naval architecture, total ship resistance is generally broken down into three main components:
            
1. Frictional Resistance (Viscous Drag)
                This accounts for the friction between the water and the wetted surface area of the hull. At low speeds, frictional resistance is the dominant force. Keeping your hull clean and free of marine growth (like barnacles) drastically reduces this friction, improving fuel economy.
            
2. Wave-Making Resistance
                As a boat pushes through the water, it generates a bow wave and a stern wave. As the vessel approaches its theoretical "hull speed" (roughly $1.34 \times \sqrt{\text{Waterline Length in ft}}$), it effectively gets trapped between its own bow and stern waves. At this point, wave-making resistance increases exponentially; adding more engine power will just create a larger wave rather than significantly increasing speed (unless the hull is designed to plane).
            
3. Aerodynamic Resistance (Air Drag)
                Though often minimal for slower, heavy displacement yachts, wind resistance becomes a significant factor for high-speed vessels or ships with massive superstructures facing severe headwinds.
            
                Note on Calculation: This calculator utilizes the Admiralty Coefficient method to estimate the required power and converts it into total resistance. It provides a baseline estimation for displacement hulls and should not replace advanced CFD (Computational Fluid Dynamics) testing for new builds.