Influence of Weber number on Surface Piercing Propellers model tests scaling

Interest in Surface Piercing Propellers (SPP) application has increasingly grown in consideration during the last years, especially in the field of fast crafts for leisure, competition and even naval application. Unfortunately, behaviour of this kind of propulsion system is still far to be completely investigated, due to its relatively recent introduction, the limited (but increasing) range of applications and the fact that data are in many cases considered as protected know-how. Among the various problems which have to be considered in the design phases of this kind of propeller, the present work addresses some aspects of scaling the performances from model tests data, and in particular the influence on Weber Number is further analysed following a series of studies performed in the last decade by University of Genoa and University of Naples, stressing its effect not only on the critical advance coefficient determination, but also on the whole typical propeller thrust and torque coefficients.