Holtrop-Mennen • ITTC-1957 Friction • Form Factor • Appendages • Wave-Making • Bulb • Transom • Correlation Allowance • Effective / Brake Power
Holtrop-Mennen Ship Resistance & Power Tool Calm-Water Resistance & Speed Curve
Estimate calm-water resistance by decomposing the hull into the Holtrop-Mennen resistance components rather than fitting a generic cubic power curve. Simple mode provides a quick bare-hull preliminary-design screen from principal dimensions. Advanced exposes the geometry and empirical terms, appendage register, bulb/transom effects, bow-thruster tunnel drag, historical regression-domain checks, speed-by-speed resistance decomposition and a transparent effective-to-brake power chain.
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Need bulb, transom, appendages, actual wetted area or detailed validity checks? Click Advanced above.Simple is a bare-hull preliminary screen with normal stern, no bulb, no immersed transom and no appendage drag. Cb and Cp are derived from displacement and geometry.PhysicsResistance components
CurveSpeed → resistance → power
CheckFn / hull-range diagnostics
Principal Particulars
m.
m.
m.
metric tonnes in 1025 kg/m³ seawater.
% LWL, positive forward.
kn.
% effective power → brake-power screen.
Hull Geometry & Regression Profile
m.
m³.
% LWL, positive forward.
Surface, Bulb & Transom
m², used only when selected.
m² at stem / still-water surface.
m.
m² at zero speed.
m; 0 disables tunnel-drag term.
Published Holtrop range typically 0.003–0.012.
Appendage Register
Appendage resistance is calculated with the ship friction coefficient and Σ[Sapp × (1+k₂)]. Factors are deliberately editable because Holtrop’s values are tentative ranges for streamlined, flow-oriented appendages.
| Use | Appendage type | Wetted area m² | 1+k₂ factor |
|---|
Water, Speed Curve & Power Chain
kg/m³.
m²/s; ≈1.188×10⁻⁶ at ~15°C seawater.
kn.
kn.
kn.
kn.
% user-entered propulsive efficiency.
% shaft/gear/transmission screen.
% applied after calm-water brake power.
Resistance Model Quality Checks
Model limitation: Holtrop-Mennen is a semi-empirical preliminary-design method derived from model-test and trial databases of conventional displacement monohulls. It is not a CFD, towing-tank or ISO 15016 trial-correction method and does not model waves, wind, shallow water, current, fouling, dynamic lift or multihull interference. Results become increasingly uncertain for unusual hull forms or outside the historical parameter ranges.