What does adding reducing diameter, and adding reducing number of blades do??? I know it is different on every application, but what is the most common things that happen??? I have heard adding blades creates stern lift. heard adding diameter also creates stern lift, and reduces slip???? if the props were spinning in, wouldnt bigger diameter and more blades create bow lift??? Also, arent three blades usually faster than 4,5,6 blades??????? Just for the hell of it say we are keeping drive height equal in all applications...

I think it depends on individual setups. Like if your particular boat has a deep drive, and minimal slip with 3 blades, a 4 or 5 blade may slow it down. However, if you get lots of slip with a 3 blade, going to a 4 blade would reduce the slip, and sometimes yield speed gains. i guess every setup is different.

I also hear adding diameter gives more stern lift. Also, usually the more blades give better bite for planing and cruising speeds. I am sure on of the prop guys on here can give you more info.

I know every set up is different but I'm looking for the general rules of thumb that they use...like usually when you do this _____ the result is this _______

On a 38 foot Cigarette.

I had hydromotive 4 Blade Clever style props and I had 24% Slip at cruising speed - 3300rpms.
I went with 5 Blade Maximus with a larger diameter and got 14% Slip at 3300rpms.
Also, all vibration was lost when I went to 5 blades.

If you go from 4 to 5 blade, reduce your pitch by 2.
You will love your cruising speed, but acceleration is slower and you may loose a little top speed unless you get the props labbed.

I personally like the setup because I am getting better gas milage and higher speeds at lower RPM. I can cruise at 50mph all day - 3300-3500rpm.

By the way, those Hydromotive props are for sale.

If I spin my props in, will a bigger diameter create more bow lift???

I don't know.
I have read a post where a Cigarette boat owner, spinning the props in, claimed he increased 4-7 mph. I don't know what props.

Hey, Its Kevin .Those tips work out for you? What I know about props.......3 blades are usually faster on the top end, but slower coming out of the hole. 4 blade has a better mid range "pull" and better cruising speed. 5 and 6 blade props are usually for boats with high x dim. or surface piercing type drives. Props spinning in or out.....different for every boat. Just try it one way, then the other. A 20 min test may give you 2-5 MPH but the handling of the boat also changes. With my 2 cents being thrown out there.....Bret at BBlades is the man to talk to about specifics. He has been right on the money with WOT speeds and how the boat will handle. Best MPH per dollar...hands down.

This is a big question and could require a long disertation. I can't offer that now but.............

More blases, diameter, blade area equals more stern lift.

Higher rake more bow lift.

Less blades, more speed if the props hook up well.

In is stern leverage, out is stern lifting.

Many more specifics and variables to be dicussed on individual basis's.

B