Ship Power Prediction - Holtrop and Mennen
The resistance estimation in this calculator is based on the empirical method developed by Holtrop and Mennen.
Statistic data from the Netherlands ship model basin has been used
by Holtrop and Mennen to develop the method using regression analysis. It has since been further expanded to also cover high-block with low L/B ratio ships and slender navy ships.
Propeller efficiency approximation is caried out using a simplified equation for the Wageningen B-series propeller.
Propeller manufactures can typically make propellers with a slightly better efficiency than
than what is optained by using B-Series propellers.
Please be aware that Accuracy is best for conventional hull forms and ship types and that this method do not account for all factors affecting the resistance and power
requirements. It can be used at a early stage of the design but cannot replace CFD and model testing.
For example see this link
See the article descriping ship form coefficients
for detailed description of some the input needed for the power prediction.
Cstern - Aft ship shape factor
The Cstern coefficient is chosen based on the aft ship shape as described in the table below.
| Afterbody form | Cstern |
|---|---|
| V-shaped sections | -10 |
| Normal sections | 0 |
| U-shaped sections with Hogner stern | +10 |