n the paper the current and future possibilities of the R-JH3 method are discussed. The R--JH3 method (presented in detail in [27]) was elaborated for the ship power prediction onthe basis of a new definition of the open-water propeller fully equivalent to the behind-the--hull propeller. The R-JH3 method can be used to determine the mean effective velocity andthe mean effective pitch coefficient of the behind propeller. The R-JH3 method may be veryuseful for scale-effect investigations and scale-effect designation when results of modelself-propulsion test have to be transformed to the ship scale