Unconventional Propulsion — Silver leaf 



0-3r 



F - WEIGHT OF FUEL (tons) 



A - DISPLACEMENT (tons) 



P - INSTALLED POWER (h p) 



V - SPEED IN CALM WATER (knots) 



0-2 - 



_F 

 A 



0-1 - 



1 ooo 



2 OOO 



RANGE MILES 



3 OOO 



4 OOO 



Fig. 7 - Fuel-displacement ratio: general (for fuel 

 consumption of 0.5 Ib/hp-hr) 



Since most ship propulsion devices operate in a nonuniform inflow, the like- 

 lihood of propeller -excited vibration, or its equivalent, is an important factor in 

 choosing the most appropriate device. As the thrust or power loading coefficient 

 increases, so the likelihood of blade-excited vibration also increases, while 

 growing nonuniformity of inflow naturally aggravates the situation even more. 



Typical Values of Propulsion Parameters 



Table 3 gives typical values of loading factors and other propulsion param- 

 eters for different types of ship and marine craft; these values show that: 



(i) The thrust loading coefficient Cj is generally less than 1.5 for all 

 types of vessel except large full-form tankers and bulk carriers 

 for which much higher values are now common; in consequence, 

 the ideal jet efficiency r/j is also generally greater than 0.8 except 

 for these large low-speed ships, for which much lower values are 

 the best that can now be achieved. 



900 



