Holtrop Analysis Report

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Report Time: 3/8/2015 4:28:20 PM

Displacement Hull ResistanceDefault Company

Model Name: C:\Users\Razvan\Desktop\Nava.3dm

of 4Orca3D - Marine Design Plug-in for Rhinoceros

WaterType Salt

CorrAllowance 0.00036096

WaterDensity 1025.9 kg/m3

FormFactor 1.2437

WaterViscosity 1.1883E-06 m2/s

Method Holtrop 1984 (mod)

DesignSpeed 14.5 kt

SpeedCheck OK

DesignMarginPercent 0

HullCheck OK

Propulsive Efficiency 50 %

Prediction Parameter Value

LwlBwlRatio 4.4254 3.9 14.9 Computed

LambdaCoef 0.79 0 0.99 Computed

BwlDraftRatio 2.66 2.1 4 Computed

PrismaticCoef 0.64 0.55 0.85 Computed

FnMax 0.253 0 0.47452 Computed

Parameter Check Value Minimum Maximum Type

BulbAreaAtFP 0 m^2

LCBFwdTransom 51.912 m

WaterplaneArea 1483.8 m^2

HalfEntranceAngle 15 deg

TransomArea 0 m^2

BulbCentroidBelowWL 0 m

SternTypeCoef 0

BeamWL 20.031 m

LengthWL 88.646 m

MaxSectionArea 149.1 m^2

WettedSurface 2475.7 m^2

DisplacementBare 8.6421E+06 kgf

MaxMoldedDraft 7.519 m

Vessel Data Value

14.500 0.253 1.648 1.384 239765.5 1788.5 239765.5

15.500 0.270 1.634 1.908 315177.4 2513.2 315177.4

13.500 0.236 1.664 1.048 188195.0 1307.0 188195.0

Speed (kt) Fn Cf (x 1000) Cr (x 1000) Rbare (N) PEtotal (kW) Rtotal (N)

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Report Time: 3/8/2015 4:28:20 PM




LCB forward of transom 0.4153 Decrease

Immersed transom area 0.061349 Increase

Waterplane area 0.43177 Decrease

Max section area 0.72998 Increase

Sensitivity Analysis Index To Reduce Drag

2. The Holtrop prediction method contains a calculation parameter (Lambda) that is used to estimate thehumps and hollows in the drag curve. Anecdotal experience and testing by HydroComp have identifiedcombinations of parameters that can produce significant errors with the Holtrop method. The relationshipbetween Lambda and length-based Froude number (Fn) has proven to be one such indicator of potentialerrors. The prediction results may be unreliable for speeds that exceed this Lambda-Fn relationship.3. The Holtrop prediction method is based on a variety of hull forms, including collections of transom-stern round-bilge hulls. As part of a broader evaluation of prediction methods for high-speed round-bilgehulls, HydroComp has identified a combination of parameters pertaining to the effect of stern geometrythat is an indicator of potential errors. The prediction results may be unreliable for speeds that exceedthis indicator.

1. The Holtrop prediction method has a defined upper limit of 0.80 for the length-based Froude number(Fn). Extrapolating speed beyond this value is not recommended.

Prediction Checks

14.500 0.528 239765.5 1788.5 3577.0 OK

15.500 0.564 315177.4 2513.2 5026.4 OK

13.500 0.492 188195.0 1307.0 2614.0 OK

Speed (kt) Fv Rbare (N) PEtotal (kW) PPtotal (kW) Prediction Check

A Sensitivity index with a higher value has a greater influence on drag. Sensitivity values greater than1.0 are considered significant.

Notes

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Report Time: 3/8/2015 4:28:20 PM




Holtrop Analysis Report

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