15x21 going to a 16X24
 

I currently have 15X21 3 blade cleavers on Speedy II's, what would be the effect of going to a 3 blade cleaver 16X24? Would it be any easier coming out of the hole with a bigger dia and pitch?

Re: 15x21 going to a 16X24
 

16x24 is a LOT more prop than 15x21. Assuming you can pull just near redline with your current power and gearing, you will find that you might not even get up into the powerband with the 16x24. If you are planning on adding a lot of power, this might be the prop. Otherwise, look for something like 15.5 x 21 or 16 x 21 to improve your blade area for hole shots.

More info is needed on your current setup to assess what would be right. Visit www.speedboatperformance.com, and try out the online calculator there. It will show you what you want to know.

Re: 15x21 going to a 16X24
 

Yes, if you could give us a little more information we can try to help. Increasing your pitch to a 24P will bring your RPM down about 600 RPM with like diameter of course. Typically the smaller the pitch the better the hole shot. What is it you are trying to accomlish?

Julie

Re: 15x21 going to a 16X24
 

Not only will it be more difficult getting on plane, it will also change the attitude of the boat.

Do you need to adjust the current rpm's of the rig?

Re: 15x21 going to a 16X24
 

I have 3 blade cleavers on it now and it is a PITA to get on plane. These props have been on for a while and the previous owner said that they worked good. I am just looking for a way to get the boat on plane easier

Re: 15x21 going to a 16X24
 

Are these TRS 's or over the hub cleavers?

Re: 15x21 going to a 16X24
 

over the hub, the lowers are speedmaster II's

Re: 15x21 going to a 16X24
 

Oops, I should of caught that right away.

Your biggest problem as you are well aware of now, is the availability of 4 inch hubs. You're also pretty much stuck with 3BL props. Mercury doesn't make any 4" props anymore. In fact 19 spline in general is a thing of the past allthough may be special ordered in 6".

Where are your rpm's at WOT? Are they correct? The props you have may be able to be completely changed to help your planing. Are these props in the ballpark?

Also give Mindy a call at Dollar MArine. They used to find me older stuff all the time. Also Alan at Supreme marine in MN.

Good luck.

Re: 15x21 going to a 16X24
 

The props you have now may have been worked at some point. A frequent problem we see with speedmaster style props that have been worked in the past is the cup is ground out. The cup will help you get on plane. If your rpm's are a little on the high side now adding some cup may be a very cost effective way to improve the boat's ability to get on plane.
The ultimate way to go would be to have Hering make a set of 4 blade props for you. It would be expensive and only you could decide if it would be worth it or not.

Matt