Hering Magic
 

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 :grinser010: 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. :ernaehrung004:

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

Prop hub extension?
 

Did it improve bow lift?
Thanks
Steve

Steve,

With proper outdrive depth, most all of the Bravo ear styled props seem to carry the bow fairly well with this hull. The 5 and 6 blade props are much smoother than a typical 4 bladed Bravo, and seem to carry the whole boat better.

The only time I have experienced stern lift with this boat, is when I have either tried a cleaver style prop, or a prop with a lot of cup. On these occasions, when aproaching speeds of 90+, I could feel the rear of the boat lift and move to one side, like the prop was walking on the water... a scary feeling.

Hope this helps,
Chris

Chris,
Did nordic rig your boat with the 600 new and if so do
you have any pictures of your hatch and seat that you
would share?

Digger,

Yes they did rig my boat new with the 600. But it had a 496 sitting in the engine bay when I ordered the boat, but no interior or rigging.

Here is a picture showing the modifications they did to the front and top of my hatch in order to clear the motor.

Hope this helps,
Chris

Thanks Chris,
looks great. did they have to more your seat forward or notch it any that you know of?

Aaron

Aaron,

No, I dont think they had to move the seat, they did notch the back of the forward lip of the hatch to clear the pulley on the supercharger.

You are going to love that motor in your boat.
Start with a 28 pitch bravo prop, and make sure that the outdrive lower shaft is aproximately 4-4.5 inches below the pad at the rear of the boat. You should see aproximately 81 mph at about 5400 rpm. Or you can use a 30, which will net you higher cruise speeds, and a top end of 80, at approximately 5100 rpm, but it lugs the motor a little.

Chris

P.S. If you send me your e-mail address, I will send you a prop/spacer table from my boat. [email protected]

IMCO Water Pressure?
 

Steve,
What maximum water pressure did you see with the IMCO drive at what rpm/mph? What pressure did you limit to by running at 3500 rpm and set the popoff to?

Thanks,

Bill

Thanks Chris,
Looking forward to it if Nordic ever gets to it. I guess they are to busy with the magic boats to deal with mine right now so loosing my patience a bit. What altitude are you running at?

[email protected]
Aaron

Bill anything over 35PSI in an open cooling system can push water past head gaskets, and in some cases (40+) break the plastic water pump housing. I've run into both with the Imco, as have others. Closed systems I don't know.
The Merc blow off valve is supposed to open @ 35PSI, but my first one wouldn't open until 40. You can reduce the blow off PSI by clipping the internal spring. This is an overpriced little plastic toy ($300), but it can save your motor.
Regards,
Steve

Thanks Steve. I record sea water pressure in the low 40's at WOT with the 496 closed cooling system and a Bravo X1. I think I am free of any plastic parts in the sea water plumbing.

Did Hering advise why the extension of the exhaust ring settled down the drive when the exhaust is above water?

Rage,

Exhaust does not go thru my outdrive or prop. The ring extension is in reality an extension of the drive, and acts like a trim tab of sorts. The water does not know that the extension is spinning. Trimmed down, the extension helps plant the nose of the boat more, by pushing up on the stern. Trimmed up, the extension pulls the stern down more, helping lift the nose of the boat.

Chris