How to divide the global resistance change into the components related to the pushing propeller and the pulling propeller of the double-ended ship

Abstract

The division of the global resistance change ∆R_R+D due to the simultaneous action of the pushing (SR) and pulling (SD) screw propellers into the components ∆R_R and ∆R_D can be done by taking into account two different procedures and different hypothetical assumptions given in the form of the division coefficients (A_j)_R and (A_j)_D, the same in each procedure.

In the procedure no 1: ∆R_R = ∆R_R+D(A_j) and ∆R_R = ∆R_R+D(A_j)_Dj

In the procedure no 2: ∆R_R = T_R – (R₀– F_D) (A_j)_R and ∆R_D = T_D – (R₀– F_D) (A_j)_D

Two necessary conditions were formulated to be fulfilled when selection of the coefficients (A_j)_R and (A_j)_D is done. The results of the analysis are univocal. Among the possible division coefficients only one pair of them fulfills the formulated conditions. This pair is:

(A₁)_R=T_R/T_R+D and (A₁)_D=T_D/T_R+D