Holtrop & Mennen Power Prediction Calculator

An Approximate Power Prediction Method for Ships

Developed by Hrithin
Vessel Particulars
Resistance Components
Propulsion Factors

Vessel Particulars

Coefficients

Displacement & Speed

Water Properties

Bulbous Bow Parameters
Transom Parameters
Stern Type

Preliminary Calculations

Parameter Value Unit
Froude number, Fn 0.207 -
Reynolds number, Rn 2.18E+09 -
Frictional coefficient, CF 0.00153 -
Wetted surface area, S 8562.3 m²
Form factor, 1+k1 1.245 -

Appendage Resistance

Appendage Configuration
Appendage Type (1+k2) Value Wetted Area (m²)
Rudder behind stern
Shaft brackets
Strut bossings
Hull bossings
Shafts
Parameter Value Unit
Total appendage wetted area, SAPP 50 m²
Equivalent (1+k2)eq 2.48 -
Appendage resistance, RAPP 184.2 kN
Resistance Summary
Frictional resistance, RF: 1,245.3 kN
Form resistance: 1,550.4 kN
Appendage resistance, RAPP: 184.2 kN
Total resistance (prelim): 1,734.6 kN

Wave Resistance

Parameter Formula Value
Half angle of entrance, iE From formula or input 20.0°
Coefficient c1 2223105·c7³·⁷⁸⁶¹³·(T/B)¹·⁰⁷⁹⁶¹·(90-iE)⁻¹·³⁷⁵⁶⁵ 1.245
Coefficient c2 exp(-1.89·√c3) 0.987
Coefficient c3 0.56·ABT¹·⁵/{B·T·(0.31·√ABT + TF - hB)} 0.012
Coefficient c5 1 - 0.8·AT/(B·T·CM) 0.997
Coefficient c7 Based on B/L ratio 0.167
Coefficient λ 1.446·CP - 0.03·L/B (if L/B < 12) 0.786
Wave resistance, RW c1·c2·c5·Ñ·ρ·g·exp(m1·Fnᵈ + m2·cos(λ·Fn⁻²)) 325.4 kN

Bulbous Bow Resistance

Parameter Formula Value
Parameter PB 0.56·√ABT/(TF - 1.5·hB) 0.373
Froude number Fni V/√{g·(TF - hB - 0.25·√ABT) + 0.15·V²} 1.245
Bulbous bow resistance, RB 0.11·exp(-3·PB⁻²)·Fni³·ABT¹·⁵·ρ·g/(1 + Fni²) 42.7 kN

Transom Resistance

Parameter Formula Value
Froude number FnT V/√{2·g·AT/(B + B·CWP)} 2.345
Coefficient c6 0.2·(1 - 0.2·FnT) if FnT < 5 0.106
Transom resistance, RTR 0.5·ρ·V²·AT·c6 28.9 kN

Model-Ship Correlation

Parameter Formula Value
Coefficient c4 TF/L if TF/L ≤ 0.04 0.078
Correlation allowance, CA 0.006·(L+100)⁻⁰·¹⁶ - 0.00205 + 0.003·√(L/7.5)·CB⁴·c2·(0.04-c4) 0.00042
Model-ship correlation resistance, RA 0.5·ρ·V²·S·CA 18.3 kN

Total Resistance

Resistance Components
Frictional resistance (with form): 1,550.4 kN
Appendage resistance: 184.2 kN
Wave resistance: 325.4 kN
Bulbous bow resistance: 42.7 kN
Transom resistance: 28.9 kN
Model-ship correlation: 18.3 kN
Total Results
Total resistance, RTotal: 2,149.9 kN
Effective power, PE: 27,642 kW
Froude number, Fn: 0.207
Speed: 25.0 knots

Propeller Details

Additional Parameters

Propulsion Factors

Wake Fraction, w

Parameter Formula Value
Viscous resistance coefficient, CV (1+k1)·CF + CA 0.00233
Coefficient c8 Based on B/TA ratio 22.4
Coefficient c9 Based on c8 value 22.4
Modified prismatic coefficient, CP1 1.45·CP - 0.315 - 0.0225·lcb 0.527
Coefficient c11 Based on TA/D ratio 1.875
Wake fraction, w Single screw formula 0.312

Thrust Deduction Factor, t

Parameter Formula Value
Coefficient c10 Based on L/B ratio 0.167
Thrust deduction factor, t Single screw formula 0.198

Relative Rotative Efficiency, ηR

Parameter Formula Value
Propeller thrust, T RTotal / (1 - t) 2,677.9 kN
AE/AO (calculated) K + (1.3+0.3·Z)·T/(D²·(po+ρ·g·h-pv)) 0.623
Relative rotative efficiency, ηR 0.9922 - 0.05906·AE/AO + 0.07424·(CP-0.0225·lcb) 1.012

Power Requirements

Efficiencies
Wake fraction, w: 0.312
Thrust deduction, t: 0.198
Relative rotative efficiency, ηR: 1.012
Hull efficiency, ηH: 1.142
Power Calculation
Effective power, PE: 27,642 kW
Thrust power, PT: 24,218 kW
Propeller power (delivered), PD: 21,485 kW
Shaft power, PS: 22,895 kW

Summary

Parameter Value Unit
Total resistance, RTotal 2,149.9 kN
Effective power, PE 27,642 kW
Required shaft power, PS 22,895 kW
Propeller thrust, T 2,677.9 kN
Speed 25.0 knots