New Prop Question - Not Pitch Related

[JStutz]

What effect does prop Diameter have on performance? I have never seen this question asked. I have a 1993 3.0L engine with a 15.3x17 Solas prop. I got the boat used last year. The boat works well and is within the WOT rpm's.<br /><br />My only complaint would be when idiling towards a dock or in a "no wake zone" the boat seems to moving fast. The idle rpm is around 800. <br /><br />I was searching the Solas website and noticed the 15.3 diameter props are "designed" for larger engines. Would I be smart to get a smaller diameter prop with the same pitch or would the lower diameter affect the pitch? <br /><br />Common sense would tell you that a larger diameter prop would be heavier to spin thus a loss in power.<br /><br />Thanks!<br /><br />Jeff Stutz

 

[mikebc]

Re: New Prop Question - Not Pitch Related

I had a 14.5 with a 17'pitch on a set up much like yours. I had my idle down to 600, try that and see, plus it will be way easier on the clutch

 

[olbuddyjack]

Re: New Prop Question - Not Pitch Related

From what i've read the the prop diameter has more to do with surface area of the blades, more blade area to push more water at less rpm. Kinda like a 4 blade, more push on the bottom but a little less speed on the top.

 

[tommays]

Re: New Prop Question - Not Pitch Related

you will find for the most part that you get to pick pitch and the diameter tends to come for the ride<br /><br />even in line X of props from the same company the dia will change with pitch<br /><br />tommays

 

[Doug Durako]

Re: New Prop Question - Not Pitch Related

If everything else is equal, one inch less in diameter increases your WOT by about 200 rpm.