Duport 3 Visconti, and Merle 



French, for instance for "Z flow" or "straight flow" propeller 

 units. 



Regarding the information contained in Figure 1 we know that 

 it may be obsolete to some extent, since we mention the date of the 

 source (1965). This discussion might be a good opportunity to collect 

 recent characteristics of propeller devices applicable to fast surface 

 ships. These informations should include not only the efficiency at 

 cruise condition but also some other parameters as the one we have 

 proposed (or equivalent) dealing with the "intermediate -speed" per- 

 formance and the weight-balance of the propeller unit. 



We agree with Dr. Morgan that the "partially submerged 

 propeller" should be included in the comparison, while keeping in 

 mind that it is suitable only when no important relative movement 

 between the ship body and the water surface can occur. 



The authors are well aware of the literature available on 

 ducted propellers, even if they are not familiar with all the methods 

 used in this field. For the sake of simplicity of experimental approach 

 they decided to carry out a "separate flow approach" as it has been 

 described in the paper. They agree that this is justified only if the 

 drag of the duct is properly taken into account, which is the case with 

 the method used. However they recognize that the justification has 

 not been clearly and sufficiently explained in the paper and they plan 

 to complement the present reply to Dr. Morgan in an appendix to 

 their paper. 



APPENDIX 

 TO THE PAPER BY J. DUPORT, M. VISCONTI AND J. MERLE 



* Water-Jet Propulsion for High-Speed Surface Ships" 



This appendix is complementing the reply to Dr. J. W. Morgan's 

 discussion. The authors also take the opportunity of bringing comple- 

 mentary information on the test of the 800 kW prototype of the "Isere" 

 propeller. 



The authors have written that "the hydrodynamics of intern- 

 al flow can be to a large extent analysed separately from the external 



30 



