PSModel a look inside

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Introduction

Quick Start

Quick Series
Facts

PSModel
Program

Data Input

Data Output

Importing a
Data file into
MS Excel

Main Menu

Main Screen

Printing
Graphs
and Data

Screen Colors
and Fonts

Screen
Graphs

Shortcuts

Working
with Data

Testing:

Test Sheet

Examples

19' Ski Boat

34' Sailboat

41' Utility Boat

Technical

Blade Area
Ratio

Calculating
the Cavitation
Number

Horsepower
Losses

Hull Speed

Kt Breakdown

Propeller
Geometry

Propeller Law

Wake Factors

Glossary

References

Data Output:

Each time the Calculate button is clicked (or the Return Key is pressed) in the Series Dialog Box a line of output data is added to the Data Window.  The sections Working With Data and Shortcuts provide information on how to manipulate this data.

When output values become very large or very small they are represented by Scientific Notation.  For example, the very large number 12,270,000,000 = 1.227 x 1010 is represented as 1.227E+10, and the very small number 0.00003403 = 3.403 x 10-5 is represented as 3.403E-05.

The following is a column by column description of the output data: 

1) Row -- output line or row number.

2) Series -- propeller series used to calculate the current row of data: e.g., NV4, B, GBD, etc.

3) Z -- input value, number of propeller blades.

4) BAR -- input value, Blade Area Ratio.

5) P/D -- input value, Pitch / Diameter.

6) Cup -- input value, propeller Cup: e.g., None, Heavy, Medium, Light.

7) Sigma -- Cavitation Number: if the Adv. Coef., J check box is checked in the Series Dialog Box then this value is input, if the MPH / RPM check box is checked then this value is calculated.

8) J -- Advance Coefficient: if the Adv. Coef., J check box is checked in the Series Dialog Box then this value is input, if the MPH / RPM check box is checked then this value is calculated.

9) Kt -- calculated value, Thrust Coefficient = T / (ρn2D4).

10) 10Kq -- calculated value, 10 x Torque Coefficient = 10 x [Q / (ρn2D5)].  The Torque Coefficient, Kq, is normally multiplied by 10 to make J vs. Kt, Kq, Efficiency graphs more usable.

11) Eff. -- calculated value, propeller efficiency = (J × Kt) / (2πKq).

12) Depth(ft) -- input value, depth of the propeller hub below the water surface in feet.

13) 1-w -- input value, wake factor = Va / V, see the Wake Factor section.

14) MPH -- input value, boat speed in Miles Per Hour.

15) ERPM -- input value, engine Revolutions Per Minute.

16) Q(ft-lbs) -- calculated value, propeller torque in foot-pounds.

17) T(lbs) -- calculated value, propeller thrust in pounds.

18) Hp -- calculated value, horsepower absorbed by the propeller = 2πQn / 550.

19) Gr. Ratio -- input value, gear box ratio.

20) Dia.(ft) -- input value, propeller diameter in feet.

21) Rho -- values in this column are a compact representation of water density, type of water, and water temperature input: e.g., Fresh water at 60 degrees Fahrenheit has a density of 1.9383 lb-sec2/ft4 and is represented as 1.9383F60; Salt water at 59 degrees Fahrenheit has a density of 1.9905 lb-sec2/ft4 and is represented as 1.9905S59.

22) Tc --  calculated value, Thrust Load Coefficient = T/{½ρ × Ap × [Va2 + (0.7πnD)2]}.  This value is used by marine professionals as an aid in evaluating a propeller's potential for cavitation.