[C320-list] Engine RPM verus SOG

[Alan Goodman]

Last Fall, in anticipation of having my propeller inspected and tuned, I
 used my GPS SOG reading to plot engine RPM versus SOG.  I was also 
interested in establishing maximum cruise range operating conditions 
(i.e. fuel efficiency). These figures are pretty accurate since they 
were obtained on flat water, no wind, and no current.  I also double 
checked them by running in the opposite direction to make sure there 
were minimal environmental effects.  I have a Perkins (not sure of the 
Hurth gear reduction) with a 15 X 9 three blade prop.  Data is presented as Engine 
RPM / SOG. Speed is in Kts.

1200 at 4.0//1500 at 4.8//2000 at 5.7//2500 at 6.7//2750 at 7.0//3000 at 7.3