Savitsky Planing Hull Resistance & Power Calculator
Calculate planing boat hydrodynamic lift, equilibrium running trim angle, wetted length, friction and pressure drag, and required power via the Savitsky method.
Vessel Weight & Hull Geometry
Operating Speed & Propulsion Efficiency
Savitsky Planing Hydrodynamics
| Beam Froude Number (Cv): | -- |
| Equilibrium Running Trim (τ): | -- deg |
| Mean Wetted Length-Beam Ratio (λ): | -- |
| Wetted Chine Length (Lc / Lk): | -- m |
| Pressure Drag (Induced Lift Drag): | -- kN |
| Friction Drag (Skin Friction): | -- kN |
| Effective Towing Power (PE): | -- kW |
| Engine Brake Horsepower (BHP): | -- HP |
Recommended Tools & Equipment
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Frequently Asked Questions
What is the Savitsky method for planing hulls?
Developed by Daniel Savitsky in 1964 at the Davidson Laboratory (Stevens Institute of Technology), the Savitsky method is the world gold standard empirical mathematical procedure for predicting the hydrodynamic lift, running trim angle, wetted keel and chine lengths, friction resistance, and induced pressure drag of prismatic planing hulls across speeds from semi-planing to fully planing regimes.
What is the ideal running trim angle for a planing powerboat?
The optimum running trim angle for minimum hydrodynamic drag on most prismatic deep-V powerboats is between 3.0° and 4.5°. Running below 2° wets excess hull bottom and creates high friction drag with bow steering tendencies, while running above 5° creates excessive induced pressure drag and triggers rhythmic vertical porpoising instabilities.
How does deadrise angle influence planing hull performance and comfort?
A flat-bottom hull (0° deadrise) produces maximum hydrodynamic lift and planes at lower speeds with minimal power, but delivers bone-jarring impact slams in chop. A deep-V hull (20° to 24° deadrise) slices smoothly through waves with gentle accelerations, but produces less hydrodynamic lift per unit speed, requiring higher power and trimming deeper into the water.