32P vs 34P Bravo I Props
 

I added a power upgrade to 525's and Imco lowers (std length) to my 34 Hustler Cheetah.

I ran 32 pitch bravos up to 89 MPH and was close to the limiter. Handling was very stable and good at 89 MPH. Boat had more to go. So I figured I was set for going up to 34's.

I ran 34 Bravos this past weekend and anything over 84 MPH was a handful. They are very stock and pretty thick blades. I think they were raising the transom too much and causing serious chine walking, almost uncontrollable. Great cruise at 80 and 4400 RPM though. But start to push over 84 and it was BAD. I think I can spin them to 5200 RPM, but not the way the boat was handling. What would cause this?

Should I get the 34's labbed and cleaned up or look for a different style prop?

Anyone?

Brett?

Throttle Up?

Bueller?

Are they turning in or out? May be worth trying them the other way.

Thats what Joe at Hustler suggested. But if I was running 90 with 32', I should run 90 with 34's without the issue too.

I have a pair of cupped 32's I'm going to try too. We'll see what they do.

Thanks for the input though. I'll be trying it too.

throttle up has a prop scanner. once a prop(or set) is scanned then you can make educated decisions and not guess!!! you can send the 32's off first. but, the real way of doing it would be sending off 2 sets and having both scanned. this way you have data to compare. they will ask all the right questions. i have seen racers struggle for years trying and guessing dozens of props and going nowhere when there is free speed and performance a few steps away.

i have no doubt that TU can find you 3mph w/o problem.

I have a set of 32's that were worked to 33's with minor "lab" work done if interested. Low hour, very good condition....I already have labbed 32's and looking for a set of labbed 30's.

The 34 Bravo 1 was the first attempt we (Mercury Racing) made at a taller than 30 pitch Bravo 1 propeller. Untill then we were only casting 30 pitch B1's and bending as needed to supply our customers needs. You have to remember this was 1999 and the HP ratings we were dealing with were less and the volume of step bottom boats were also less.

Once we built the propeller we realized a few issues which I wont go into. But, the propeller does have a few personality traits. One is the diameter is more true to advertised numbers than its earlier siblings. Two, the geometry of the prop per the pitch and the progression and the diameter tend to create some issues with performance. The most common issue was planability. This can be rectified with some minor adjusments.

In the case elite is describing, the additional diameter and the added pitch can create extra stern lift. Each boat has a personality of their own too which can create changes in boat running attitude once a certain pitch or diameter level is reached.

I like the idea of inwardward rotation as a test. Of course being careful since the boat will respond differently. Otherwise, propeller adjustments specific to your finding are a great option.

audacity, we all have scanners. Scanners don't tell you what to do to a prop to make it perform on a Cheetah or a Outlaw or a MTI. It's experience that gets that done. Scanners are great tools in the right hands and a great sales pitch in the wrong hands.

Brett

"audacity, we all have scanners. Scanners don't tell you what to do to a prop to make it perform on a Cheetah or a Outlaw or a MTI. It's experience that gets that done. Scanners are great tools in the right hands and a great sales pitch in the wrong hands"

could not agree more. and just because it works on one cheetah doesn't mean it will work on yours.

Be ready Brett...you might be getting these props soon!!!

Thanks for the excellent insight.

Kirk