Lindgren, Johnsson and Dyne 



Prop. No 



IForu prop.) 

 1.0 

 1.0 

 0.99 

 0.67 

 0.66 

 0.69 



PIZ50 PIZSt tConlrtirot.) 



,V370 Pt37t (Contrarot. ) 



"^SlS/K Tip vortan and bock 



ihe«t cavitation 

 I II 1 1 III Bock: bubble cavitation 

 ////// Foc0 cavitation 



2000 



4000 



6000 



8000 



10000 



I2000 



r/v/ 



Fig. 21 - Tanker project. Incipient cavitation curves. 



propellers, P1172 and P1123. The advantage in decreasing the load near the tip 

 is, however, obvious, i.e., the radial circulation distribution appears to be the 

 most important parameter. 



A great number of ducted propeller configurations have been tested for the 

 same project (see also Sec. 6). The cavitation test results are described in 

 more detail in (17). It is concluded that most of these propellers are compara- 

 ble with the conventional propellers with regard to cavitation properties. 



In Fig. 21, also, the best ducted propeller from an efficiency point of view, 

 P1315 D6, is compared with the other types of propellers with regard to incipi- 

 ent cavitation. A curve representing a conventional propeller, designed by use 

 of the vortex theory, P1313, is included for comparison. Both P1315 D6 and 

 P1313 have considerably better cavitation properties than the SSPA 5.60 pro- 

 pellers. 



Container-vessel project. For the container project only contrarotating 

 and conventional propellers have been investigated. Curves of incipient cavita- 

 tion for a conventional SSPA 4.60 propeller and the contrarotating set of propel- 

 lers from the systematic series, described in Sec. 3, have been presented in 

 Fig. 22, together with a set of wake-adapted, contrarotating propellers, P1319, 

 P1348. Also in this case a slight advantage with contrarotating propellers was 

 obtained in comparison with the SSPA 4.60 propeller. 



1294 



