PSModel a look inside

HOME

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

Horsepower Losses:

To obtain an estimate of the maximum available horsepower at the propeller, reduce the maximum engine rating for each of the following items that are installed:

Item Estimated % Reduction in
Engine Horsepower
Notes
Reduction Gear 3 reference 8 indicates that losses can be as high as 5%
Shaft Bearing 1 reference 9 indicates losses may be as high as 1.5%
Packing Gland 1 use 1.5% if new packing installed

Notes:

1) Some engine manufacturers may rate their engines at the output shaft of the reduction gear, so the reduction gear and parasitic load losses are already included in the horsepower rating of the engine.  Check with the engine manufacturer if in doubt.

2) Parasitic loads\losses caused by alternators and raw water pumps may or may not be included in the engine horsepower rating.  Check with the engine manufacturer if in doubt.  If unable to determine, and boat testing indicates that the engine is not delivering the rated horsepower, assume horsepower losses of 1.5% for each alternator and each raw water pump installed.