Navigation:  Speed/Power Analysis > Planing Hull Savitsky Prediction > Planing Hull Analysis Output

 

After clicking OK in the Planing Analysis dialog box, a separate report window will open with the planing hull analysis results providing the following output values:

 

Prediction Parameters

 

Method: an enhanced version of the Savitsky general case method for resistance calculations of a planing hull.

 

SpeedCheck: Confirmation that your range of speeds is within the valid minimum and maximum values, based on FnBch (Froude number, based on effective planing beam).

 

HullCheck: This is a summary of the checks on the parameters of deadrise angle, LCG location, and lift coefficient. If any of these are outside of the valid range, it will be flagged here. Each of these parameters is listed individually below in the Parameter Check section.

 

DesignMarginPercent: the user-defined margin used to account for the differences in the current model and the final design.  This can also be used to account for loss of efficiency due to wind, waves, appendages, shallow water, etc.

 

DesignSpeed: the user-defined “operational” speed of the vessel.  This speed is used in the drag reduction sensitivity analysis.

 

WaterType: the type of water used in the planing analysis.  This can be changed in the Orca3D Properties dialog box.

 

WaterDensity: the density of the water used in the planing analysis in the units specified.  This can be changed in the Orca3D Properties dialog box.

 

WaterViscosity: the viscosity of the water used in the planing analysis in the units specified.

 

Propulsive Efficiency: the user-defined propulsive efficiency used in the analysis.

 

Vessel Data

 

This section provides calculated and user-defined values defining the planing surface and vessel being analyzed.

 

MaxPlaningLength: the calculated overall length of the planing surface.

 

MaxPlaningBeam: the calculated overall beam of the planing surface.

 

DisplacementBare: the user-defined bare hull displacement in the units specified.

 

LCGFwdTransom: the user-defined longitudinal center of gravity measured from the transom in the units specified.

 

VCGAboveBL: the user-defined vertical center of gravity measured from the baseline in the units specified.

 

ShaftAngle: the user-defined propeller shaft angle in degrees relative to the baseline.

 

LCEFwdTransom: the longitudinal center of effort of the propeller measured from the transom in the units specified.

 

VCEAboveBL: the vertical center of effort of the propeller measured from the baseline in the units specified.

 

Parameter Check

 

This section verifies the following calculated parameters are within a defined range to ensure accurate results.

 

LCGPerBch: the ratio of the longitudinal center of gravity forward of the transom to the maximum planing beam.

 

FnBchMax: the maximum calculated Froude number based on the maximum planing beam at the design speed.

 

DeadriseMidLen: the angle of deadrise at the mid-length of the planing surface.

 

CLBmax: the maximum value of the lift coefficient for the wetted planing area at the design speed.

 

Results Tables

 

The two tables provide the following results for each of the user-defined speeds:

 

Fnv: the volumetric Froude number for the corresponding speed defined as Fnv = Speed/(g*DisplacedVolume⅓)½

 

Trim (deg): the predicted trim of the vessel at the corresponding speed.

 

Rbare (N): the predicted bare hull resistance at the corresponding speed.

 

Rtotal (N): the total predicted resistance including the user-defined design margin at the corresponding speed.

 

PEtotal (W): the calculated total effective power of the vessel including the design margin at the corresponding speed.

 

PPtotal (W): the calculated total propulsive power of the vessel dependent on the user-defined propulsive efficiency.  For example:

 

 

 

PPtotal is defined as the total effective power divided by the propulsive efficiency and will be representative of the power defined by the propulsive efficiency input.

 

FnBch: the Froude number calculated using the effective planing beam at the corresponding speed.

 

Eff Planing Beam: the calculated effective planing beam of the wetted planing area.

 

Eff Deadrise (deg): the calculated effective angle of deadrise of the wetted planing area.

 

Rbare/W: the ratio of the predicted bare hull resistance to the bare hull weight at the corresponding speed.

 

Porpoising: the projected porpoising stability of the vessel: Stable, Unstable or Check.

 

Prediction Check: at each speed the predicted condition of the vessel is checked against known valid ranges for the Savitsky method.  The output is either OK, or specifies “Check=” followed by the number 1 through 4.  The report provides the definition of each type of warning under the Prediction Checks section.  We caution against using results where a prediction warning is found.

 

Sensitivity Analysis

 

The report provides a sensitivity analysis to reduce drag performed at the design speed.  A sensitivity index with a higher value has a greater influence on drag.  A value greater than 1.0 is considered significant.  The third column of the table indicates if the value should be increased or decreased to reduce drag.

 

Results Plots

 

The last page of the report provides plots of bare and total hull resistance versus speed, total effective power and total propulsive power versus speed, and trim angle versus speed.