proper prop size

dank77

Recruit
Joined
Jun 11, 2003
Messages
3
Just puchased a 1991 18' celebrity bow rider,4.3l mercruiser.was told that it had a 21pitch prop,top end RPMs is in between 4400-4800.Was hitting about 5100.Went and bought a 23pitch, put it on and noticed that the old one was actually only a 19 pitch.So now for the ? is this gonna be that BIG of a deal,or should i take it back and go with a 21? the boat is used only as pleasure occasonally tubing.<br /><br /> thanks :)
 

dank77

Recruit
Joined
Jun 11, 2003
Messages
3
Re: proper prop size

forgot to add thatthe old 19 was stainless steel, the new one is alluminum
 

Doug Durako

Chief Petty Officer
Joined
Nov 17, 2002
Messages
519
Re: proper prop size

An increase of 4 inches in pitch will drop you about 800 rpm at wide open throttle. (200 rpm per inch of increase).<br /><br />Aluminum will not perform like Steel, but is more forgiving if you hit something.<br /><br />The 23 pitch will be sluggish out of the hole compared to what you had.<br /><br />Can you test a 21-pitch before you buy? That is always the best way. No two props run exactly the same.<br /><br />Lots of other prop discussion out here on the board right now.
 
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