I think I am at the end of road for this round of testing.

I just don't see my boat going any faster or more efficiently without more horsepower (Which will not happen this year)

With the help of Jeff and Ben of Hering propellers, my boat ran a consistent 93.5-94 mph today, with a best of 94.2 mph @ 5870 rpm.

Critical info:

IMCO SC drive with the propshaft depth in relation to the keel being 3.5"

Hering 28 pitch, 5 blade bravo prop at 15.25" diameter

Prop trim ring flange removed and the ring extended to aid in settling down the rear of the boat and promoting bow lift.

Thankyou Hering !

Hey Chris,
Great #s and a nice looking prop.
Do you still have the 28" P-5X? We are working on Mayor McCheese's 96 Heat, and may be able to run it.
The XD on these older boats was 16#s (really deep), and we just put a 2" Imco shorty on it. As usual, the water pressure went through the roof, and we couldn't run over 3500, so we've order a blowoff valve. We'll test props again next week.
Regards,
Steve

Steve,

I still have the 28 P5-x, and it is still for sale.

Thanks,
Chris

Those are real impressive numbers. Congrats. That prop looks funny with the extended ring. But it seems to do the right thing for your Heat and that's all that matters. Good Luck and Be careful.

Is that a supercharged engine or normally aspired?

Good numbers!! Is it difficult to get on plane with this prop? Which prop has more low end pull? Bravo, Herring or PX5?

Supercharged - Mercury Racing 600sci, with a Whipple Stage II upgrade kit (750hp)

Chris

Ahhh... now that is an educated and good question.

So here is the answer;

The three props in question are a 28 P5x modified by throttle up, a Mercury Bravo 30 pitch (really a 29) that has been sharpened and balanced, but not thinned or cupped, and a 28 pitch, 15.25" Hering 5 Blade bravo with a trim ring extension.

Having run all of them at various depths, the best setup for the Hering is no spacer (3.5" propshaft depth), the best for the P5x is a 1/2" spacer (4" propshaft depth), and for the Bravo, a 1" spacer(4.5" propshaft depth)

I have checked all these props for midrange speed, acceleration, and top end, at all of these depths.

28 P5x - Best bottom end acceleration to 40 mph, with the top end being 90.4 mph. Midrange cruise speed is the same rpm as the bravo.

30 Bravo - Explosive acceleration in the midrange from 30-85 mph. Not as good coming out of the hole as the P5x, but acceptable, top end speed of 92.1

28 Hering - This prop was difficult to get out of the hole.. especially before the hub extension was added. The extension helped, but it still spins the prop while trying to get on plane. Midrange speeds are down 3-4 mph compared to either the bravo or P5x. I believe this is because the prop has very little cup. Top end speed is consistently above 93mph, with the best being 94.2. Midrange acceleration is down compared to the other two props.

Tim has a Hering 29 that is 15.25" diameter, and has cup added. His prop is up about 3-4 mph up in the midrange compared to the other props . It also does a consistent 93mph, but on my boat, it chine-walks violently above 88 mph, and the last 5 mph are a scary dance.

The p5x is the most stable at speed in any kind of water. The bravo will chine slightly on smooth water, but it is controllable. The Hering will chine somewhat above 92 mph, but is controllable.

In processing all of this, my favorite everyday prop will probably be the Merc 30, with a 1 inch spacer. I am going to have Brett at BBlades build me a 30 to see if he can improve on the top end performance without loosing the good points of this prop.

For all out speed runs, The Hering is the natural choice, with no spacer. I will continue working with Hering to see if I can get this prop to perform better in the bottom and midrange.

This is my report.. I am definitely having fun testing.

Chris

greta info to hear

New favorite prop:

Awsome acceleration and hook-up everywhere

Hering 15.25" - 28 pitch - 6 blade

1/2 inch spacer

3000rpm = 44mph
4000rpm = 64mph
5750rpm = 93.5 mph

Chris