woodington1

35' Fountain '04 Lightning w/ 525s - Twin Step w/B-1 stock, 32 pitch, 5300 rpm, 91 Gps

16% prop efficiency is too much in my book even though speed is great!

Has anyone tried spacing lower unit by 1" w/same prop
or 5-blade props w/same stock X dimension?

I'm interested in knowing your performance numbers. I don't know which direction to take. Your input will help and might save me a few bucks!

bbladesprops

I see a true slip of about 13%.

You may recieve different reponses bit, I like the 4 blades with your slip %. 5's will slow down the top end. Spacer's are cheaper than 5 blades. No guarenteess the added drag from the cases won't outweigh the new slip either. I'd still do spacers and Lab the 32's.

bglz42

Woodington, pm CAPTWK. He has a set of spacers from his Sonic. He went with 2", so he took the 1" off.

throttleup

Woodington1,

When calculating your slip, if you are using Bravo I propellers, you need to deduct 1 inch from the pitch. The Bravo I propellers are actually 1 inch less pitch than the pitch stamped on the propeller. Assuming that you have a 1.5 gear ratio then you indeed have 13% slip. This actuall falls in the exceptable range for 4B slip. I would not recommend a spacer for your application, agian if indeed you have 1.5 gears. A 5B propeller will have about 15% slip, but you do need to drop down 1 inch of pitch to compensate for the drag of the additional blade. So, sometimes it is indeed a wash trading pitch for RPM. Typically we see 5B propellers run similar top end within 1.5 MPH on top. The benefits of the 5B propellers are the icreased cruise speeds, improved hole shot and improved acceleration. But as far as increasing your top end you are about there. If your props are stock then you could consider lab finishing a taller pitch 4B to pick up some additional speed on top.

Julie

woodington1

If I decide to go with 5-blade and blueprint, what pitch do you reccommend - hoping to retain top-end? (Running stock 4 blade 32P now.)

throttleup

I would recommend the P5-X in a 30P. This should run about the same RPM.

Julie

bbladesprops

With your current slip percentage, the 5 blade will most likely slow down your top end. You will need to go down in pitch to maintain the same rpm. The combination of decreased pitch and additional drag wont add up. If you want cruise speed, I'd concider the Maximus or P5-X.