Whats your slip?

Jay Martin

BBM Prop Doctor
Joined
Jan 12, 2009
Location
Greenville, Ms
#1
I have posted a thread in the past about prop slip and thought I would
bring up the subject again, the reason why is because of a prop that I
tested out on my Allison. The prop is a Hydromotive Q-IV O/T 30P.
I have a very odd gear ratio for the horse power and boat that I have, my
motor was born a 150 Yamaha Pro-V and is now 260hp, this engine came
with 2.0:1 gears.
I ran this prop 86.51 mph/gps @ 6300 rpm, doing the math equals to 3.3%
slip.
Your average bass boat is in the 10-12% range, some boats being higher.
The lower this number will give you results in two different ways.

1. Better fuel mileage
2. Higher top end speed

If your running an out of the box stock prop, chances are you can lower
your numbers by doing a Balance and Blueprint.
What this does is gives your engine back the horsepower that it was using
to turn the out of balance prop to produce more speed. A B&B is simply
making all blades perfectly the same in pitch, rake and weight.

Use this link to check your slip.
http://www.mercuryracing.com/propellers/propslipcalculator.php