Ship Power Prediction - Holtrop and Mennen

The resistance estimation in this calculator is based on the empirical method developed by Holtrop and Mennen. Statistic data from the Netherlands ship model basin has been used by Holtrop and Mennen to develop the method using regression analysis. It has since been further expanded to also cover high-block with low L/B ratio ships and slender navy ships.

Propeller efficiency approximation is caried out using a simplified equation for the Wageningen B-series propeller. Propeller manufactures can typically make propellers with a slightly better efficiency than than what is optained by using B-Series propellers.

Please be aware that Accuracy is best for conventional hull forms and ship types and that this method do not account for all factors affecting the resistance and power requirements. It can be used at a early stage of the design but cannot replace CFD and model testing.

For example see this link

See the article descriping ship form coefficients for detailed description of some the input needed for the power prediction.

Cstern - Aft ship shape factor

The Cstern coefficient is chosen based on the aft ship shape as described in the table below.

Afterbody formCstern
V-shaped sections-10
Normal sections0
U-shaped sections with Hogner stern+10

Ship particulars

PropertySymbolUnitValue
Waterline length at TL[m]
Beam at the watelineB[m]
DraftT[m]
Displacement at T∇[m3]
Longitudinal center of buoyancy forward of 0.5L as a percentage of Llcb[%]
Midship section coefficientCM[-]
Water plane coefficientCW[-]
Wetted surface area - Estimated if 0 is enteredS[m3]
Aft ship shape factor (See table above)Cstern[-]
Half angle of entrance - estimated if 0 is enterediE[o]
Max speed for the power predictionVs,max[knots]
Bulbous Bow
Transverse sectional area of the bulb at the position where the still-water surface intersects the stemABT[m2]
Position of the centre of the transverse area ABT above the keel linehB[-]
Transom
Immersed part of the transverse area of the transom at zero speedAT[m2]
Appendages
Forward bow thruster diameterdBTO[m]
AppendageSymbolUnitWet area of the appendage
Rudder behind skegSapp[m2]
Rudder behind sternSapp[m2]
Twin-screw balance ruddersSapp[m2]
Shaft bracketsSapp[m2]
SkegSapp[m2]
Strut bossingsSapp[m2]
Hull bossingsSapp[m2]
ShaftsSapp[m2]
Stabilizer finsSapp[m2]
DomeSapp[m2]
Bilge keelsSapp[m2]
Input for propulsion factor estimation
Propeller diameterD[m]
Number of propellers
Stern type
Relative rotative efficiency (typically between 0.95 and 1.05)ηR
Shaft efficiencyηS
Service allowance[%]