Correlation allowances in model tests results

AuthorsKarola van der Meij, Gerco Hagesteijn and Patrick Hooijmans
Conference/JournalOMAE ASME 35th International Conference on Ocean, Offshore and Arctic Engineering, Busan, South Korea, 2016
DateJun 19, 2016
A delicate balance between performance, accuracy and commercial interests?
Up to now research institutes perform model tests to determine the performance of a ship at full scale. For merchant vessels, things are not to straightforward as one would like, as already pointed out by Hooijmans. Sea trials are performed at ballast draught and these sea trials results need to be converted to the contractual design draught using model test results for both draughts. When extrapolating model tests results to full scale values, whatever extrapolation method used correlation allowances will be used to come to a prediction. The present paper deals about the daily practice with regard to the use of correlation allowances in model test results and their effect on the trial performance prediction. A large spreading in the values of the correlation allowances for design draughts can be seen for merchant vessels, but at ballast trial draught the spreading is much less. Can it happen that some institutes on purpose select favorable correlations allowances? Or should we accept a large spreading in correlation allowances and have these indeed been confirmed by sea trials at design draught? Some statistical analysis will be presented, as well as a discussion on the accuracy of model and full scale tests.
Tags
measurements and controldata sciencetransport and shippingmodel testingmonitoringshipsfull scalecorrelation