Outboard Propeller - Shorter Pitch

[LConrad]

I just changed from a 3 blade standard prop with 7.5 inch pitch to a 4 blade 5 inch pitch on my CP-23 with a Tohatsu 9.8 Hp outboard.  One advantage is slower boat speeds at idle.  Engine idle rpm did not change but boat speed dropped for a slower approach to the dock.  Also the engine does not seem to be straining as much, although running at a little higher RPM.  Prop calculations suggest a few tenths over 5 inch pitch so it is very close to max 6,000 RPM at full throttle.  I stay back just a little from full throttle. 

For the technical folks, you can try the following spreadsheet calculator
http://www.alberg30.org/maintenance/MechanicalPropulsion/Propeller/propcalc.xls