Four Screw Powering Experiments: Data Reduction, Extrapolation and Correlations

Methodologies and algorithms used for model powering experiment data collection, data reduction, and extrapolation to full scale arc presented in this paper. While the algorithms are tailored to four screw ships they can be generalized to the arbitrary case of a model which has unequally loaded sets of propellers. Algorithms for the prediction of maximum ship speed, based on shaft revolution rate, torque or delivered power limits are presented. Correlation of model powering experiment predictions and full scale trials data show that model experiments consistently under predict the inboard/outboard torque ratio. Possible explanations for this phenomenon are given.