EmPower
Empirical Power Prediction Program
EmPower is a Windows based program designed to predict resistance and performance for conventional ships.
The program is based on MARINTEK’s resistance and propulsion database, and other prognosis tools developed at MARINTEK. Further development and customization is being conducted as part of the SKIPRO 2001 project "Empirical and Experimental Determination of Ship Resistance". The program is currently only available to participants in this project. The project is still open for new participants to take part.
The current version of EmPower runs under Windows NT/95. Each institution or company using the program maintains their own database of model test results. Import and export functions makes it easy to add new results from model tests at MARINTEK.
The following calculation methods are available for resistance and propulsion data:
- Direct input of resistance and propulsive coefficients from previous model tests (database) or other calculations.
- Holtrop 84 method.
- Model resistance based on Hollenbach 98
Ship speed can be predicted by applying data from standard propeller series, including open and ducted propellers.
The program basically consists of three separate sub-programs or tools, which can be applied separately or together to obtain the information you need (see Figure 1)
Figure 1. EmPower program structure
First of all, a database containing model test results of resistance and propulsion characteristics is included. The database functionality includes filtering of vessels with regard to various parameter ranges, such as vessel types, Lpp, L/B etc. in order to select a basis for a performance prognosis for a similar ship. In addition, various reports and plots can be generated based on the filtered vessels.
Figure 2. Results database and filter criteria dialog.
The plotting module in the database includes plotting the residuary resistance in a curve fitting toolbox, where a polynomial for the residuary resistance curve can be created and modified based on the filtered vessels. This polynomial can be applied in the performance prediction part of the program in order to perform performance predictions for a given set of ship data.
Figure 3. The curve fitting toolbox.
In addition to the database, there is also a performance prediction tool which can be applied to carry out performance predictions based on Holtrop’s method or by specifying the resistance and propulsion data directly. In the latter case, the results database can be applied to find the necessary coefficients, such as residuary resistance and average propulsive coefficients.
Figure 4. Performance prediction im EmPower.
The third component that is included in EmPower, is a propeller optimization wizard, where the propeller diameter and/or pitch ratio can be optimized based on the engine and ship characteristics.
Figure 5. Propeller optimization.
Together, these different sub-programs form a basis to carry out complete performance predictions of ships based on empirical and experimental data.
PDF-file of EmPower-presentation.
Contact persons at MARINTEK: Dariusz Fathi