Well, I dont care about top end speed, just looking for something to get me on plane faster and have a better handling cruise. Will the four blade not help with pulling a skier or tuber? What are the down sides to the four blade vs three blade props? I figured I would lose some MPH but dont know if there will be more vibration..........[/quote]
Like Borchick says, you will increase surface area. You also tend to lose diameter, so I have noticed a less net effect in changing blade count. In my case, I went from 19P 3 blade SS to a 21P 5 blade SS. My top end speed and WOT RPM was changed by less than 2 MPH by GPS. However, my hole-shot was completely different, as was my handling in hard turns.
My $0.02.... find the perfomance you are after in a 3 blade prop first; then step to a 4 (ideally step up 1" in pitch). If you are going from 3 blade to a 5 blade prop, I recommend stepping up 2" in pitch. Otherwise you end up with a collection of "unique" props. 3 blades are easy to trade in at most prop shops (undamaged), or sell outright.... and always good to have one as a spare.
Use this
Prop slip calculator. It has saved me money on props.
I have found
Mid west to have the best prices and service on props.
Good luck!
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Walt B
"Debt-Charged"Black '07 H210SS6.2L Bravo One turning a 21P HIFive
Wakeboard Tower with Perfect Pass Stargazer version
Missouri River; Kansas City, Mo.