Correlation of speed-power predictions by model tests


Speed-power prediction plays an essential role in ship design. At MARIN the unique combination of model-scale and full-scale services are present, generating a wealth of high quality validation material to provide our customers with reliable power predictions.


D


Michiel Verhulst m.verhulst@marin.nl


espite the increasing role of numerical methods, speed-power prediction by model tests is still


the most reliable way of assessing the powering characteristics of a ship in calm water. This prediction process should be well validated by comparing extrapolated power measured on a model in the towing tank, with full-scale values measured during the ship trials. The MARIN ship-powering database contains geometric descriptions of thousands of ships, together with the results of the open water, resistance and propulsion tests. When full-scale speed trial results are obtained these are also added to the files. This database was used to develop the well-known Holtrop-Mennen method and can conveniently be used for correlation studies. Figure 1 shows the number of speed-trials included in the database per


2005 1818


Vortex Induced Vibrations & Motions


ship type. For these full-scale results (which includes several series of sister ships) the corresponding model test data is also available.


Large ship-powering database Over time, the amount of correlation material steadily grows because owners and builders see the importance of providing the model basin with feedback. Furthermore, the MARIN Trials & Monitoring department generates a lot of accurate and valuable data, where internal procedures make sure all full-scale data is linked to the right model-scale data if available. The speed trials are conducted, measured and ana- lysed according to the standards of the Sea Trial Analysis (STA) Joint Industry Project. In calm water model testing extrapolation methods are required to predict the full-scale power and rotation rate from the


2005


Joint Venture SSSRI China


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