MikaylaHunterCig

What is the best production prop for top speed.
38' twin step Donzi ZR W/ 500 efi's & XR ITS Drives.

Dave

throttleup

When we were working with the Donzi factory race team on the Super V all the testing was done with the 525's. We tested every prop, pitch, # of blades, different drive heights you could imagine. The Hering 5 blade props gave a mile or two on the top end but at the sacrifice of acceleration. The Hydromotive P 5 had better acceleration but they were a mile or two shy on the top end.

Depending on the weight of your boat, with the HP 500's, you may find the P5 has the same or better top end as the Hering's.

Once you have decided on the prop then you can finish dialing the boat in around the prop.

Matt

bbladesprops

This is a tough question to answer because every 38ZR is different. A race boat has a much more controlled C.G. than the consumers boat who loads it differently. Also, team race boats are laid up a little differently.

When the ZR's first came out, the fastest props we saw on them were the Lab Finished Bravo 1's we were doing while at Mercury Racing. We still find them to be the fastest propeller if the efficiency of the boat is good. This means the drive height is correct and the weight and balance is good. This has been the "fastest" propeller but not necessarily the best all around propeller. We have found 5bl props from Mercury, Hydro, and Herring to offer better cruise speeds and other personalities.

We would suggest checking the numbers with your current set-up. Improving that as needed, then deciding on the goals you wish to achieve before deciding on the propeller. Once you know where you wish to end up, it will be easier to decide the correct propeller and work needed to be done to it.

throttleup

Dave,

Are your motors side by side? The F2 Race boat runs several props but we did have the opportunity to run the Hydro P5-X props on thier boat. They ran great and produced greater top end than thier Bravo I Lab Finished propellers. Post some of your numbers .

Julie

MikaylaHunterCig

Thanks for all the info . It's really appreciated.
I will be in touch as i am dying to squeeze every bit i can top speed.
My current mid range is unreal w/ labbed bravo 32p bu the RPM is down.

Dave

customryder

Dave,
The five blade hering has worked best so far for me. the Hydro px-5 had a porpoise as higher speeds. no better cruise speed did plane very well. the Bravo is good. but the Hering give me 4-5 mph @ 3000rpm 6-7 mph
At 3500 rpm + 2-3 mph top end. planning is a little tricky you can blow them out easy. (no diffuser ring) the best i have seen so far is 95.3 5300 rpm, with the Hering. (8.1% slip) the Hydro & Bravo were 91-92. i was told a diffuser ring helps planing on the Hering.