Unconventional Propulsion — Silver leaf 



Table 3 

 Propulsion Parameters: Typical Values 



(ii) Similarly, the power loading coefficient Cp is less than 2 except 

 for such extreme ship types, although foilcraft in the take-off con- 

 dition also have high values of both c^ and Cp . 



(iii) The quasi-propulsive coefficient -q^ generally has lower values 

 for high-speed craft than for larger ships of all types, although its 

 value is not directly associated with either C^ orCp . 



(iv) The speed-displacement ratio v/Ai'^ is a parameter of major im- 

 portance for almost all conventional ships it rarely exceeds 4, but 

 for unconventional high-speed craft in calm water it may have a 

 value as high as 50. As this speed coefficient increases, the spe- 

 cific power P/AV increases sharply and thus the power-weight char- 

 acteristic of the propelling machinery becomes more important. 

 Further, as the speed-displacement ratio increases the cavitation 

 index a^ decreases significantly, indicating the much greater im- 

 portance of cavitation effects on propulsion devices for high-speed 

 craft. 



902 



