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Prop diameter BF50A

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"Currently running 11-1/4 x 13

"Currently running 11-1/4 x 13P aluminum prop which works fine. WOT is approx 5800 rpm's , 28 knots
I am looking a stainless prop 10-1/2 x 13P and wonder if the diameter decrease will have a negative effect ?
I understand that prop diameter can adjust + or - by 1/2" without any discernable change."
 
"Under normal circumstances, d

"Under normal circumstances, dropping 3/4" in diameter with the same pitch should increase engine speed by about 300 rpm. However, that puts you slightly over the 6,000 rpm limitation on the engine, so it may limit out at about 6,000."
 
How much speed do you think i

How much speed do you think i would lose at top end?
would the added rigidity of the stainless prop compensate ?
 
"Scott - it's hard to esti

"Scott - it's hard to estimate. It all depends on your hull and the max RPM you reach. Rigidness between an aluminum and SS prop in those diameters is normally not an issue. I suspect there will be little difference in speed, if any. I've used both on motors running from 60 hp to 225 hp, and I cannot tell the difference. Where you will see a major difference is in playing with the pitch. You want to have WOT at right around 6,000 rpm. On another discussion about props in this forum, one of the responders gave a website for calculating optimum diameter and pitch for various type boats and hulls."
 
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