van Manen and Oosterveld 



The propeller designs for both ships were based on 16,000 metric DHP at 

 120 rpm, and with ship speeds of 16.5 knots for the tanker and 20.5 knots for the 

 cargo liner. The conventional screws were designed according to the circulation 

 theory for wake adapted propellers. The principal full-scale characteristics of 

 the propellers are given in Table 3; further details of the conventional screw 

 propellers for the tanker and the cargo liner are presented in Figs. 7 and 8. 

 The particulars of the contrarotating propellers for the tanker (set 2) and the 

 cargo liner (set 4) were already presented in Fig. 2. 



0.9R 

 0.8R 

 0.7R 

 0.6R 

 0.5R 

 0.4R 

 0.3R 

 0.2R 



Pitch distribution 

 percent 



Fig. 7 - Particulars of single screw for tanker 



1,0R_ 

 0.9 R 

 0.8 R 

 0,7 R_ 

 0.6 R_. 

 0,5 R 

 QA R_ - 

 03 R 1 

 0J2R_: 



Pitch distribution 

 in percent 



Fig, 8 - Particulars of single scre-v 

 for cargo liner 



Model Resistance and Self- Propulsion Tests 



Model tests have been carried out to obtain a comparison of the propulsive 

 quality of the tanker and the cargo liner both equipped with successively contra- 

 rotating propellers and a conventional screw propeller. Resistance and self- 

 propulsion tests were conducted in the deep-water basin of the Netherlands Ship 

 Model Basin, in accordance with established procedures. All model data were 

 extrapolated to full-scale ship values using Schoenherr's friction coefficients 

 with an addition of 0.00035 for correlation allowance. For turbulence stimula- 

 tion, a trip wire of 1-mm diameter was fitted to girth each model at a section 



142 



