MnHowardCat

I'm playing with a prop slip calculator on the BAM website. How can I reduce slippage? According to the calculator I'm at 26%. I have a straight bottom 38 Top Gun with motors at 778hp and 795hp at 5300rpm and running 84mph with XZ Bravos with 1.5 gears and labbed 34 pitch bravo 1 props. I have to trim way out for 84mph. Boat weighs approx. 11,500. Any suggestions appreciated.

Thanks, Don

throttleup

To start with use a pitch of 32 when calculating your slip with the 34 Bravo 1 props. As the Bravo 1 props get into the taller pitch range they really start to fall shy of the marked pitch.

Consider trying a lower pitch prop and increase the rpm of the motors. This may also reduce the slip. Your rpm seems low for the horsepower produced. A lower pitch prop will not lift the stern as much thus reducing the slip.

It also depends on how your props were worked when lab finished. Diameter and cup have an influence on the slip.

There are many other causes of excessive slip but this is a good place to start.

Matt

bbladesprops

The 34 Bravo 1 propellers are unique. Labbing can really increase their slip.

What rpm do you need to turn the engines at WOT? A special recipe Lab on 32's may read bigger rewards.

MnHowardCat

Matt I sent Julie my dyno sheet's about four weeks ago and followed up with an email but she must have been busy because I never heard back/ The prop's were labbed at Throttleup the numbers stamped on the props are
M4687
M4688
I bought the props from Jeff Jennings off his 37 Outter Limits. I was wondering if they had some cup taken out of them for the step hull??? I just don't know what to try.
Don

MnHowardCat

throttle-up did you get me pm??
Don

throttleup

Hello Don,

No PM's, but call me and we can talk about the Dynos and the props.

Julie
Throttle Up PRopelelrs
727-531-2255