sommerfliesby

Repropping due to new power and shorties...need some suggestions from those in the know...

1995 35 single step, blueprinted hull
IMCO extension boxes
-2 shorties
Appr. 550 hp each

With my old 502s and std length drives, I was turning about 4850 rpm on 26 Hydromotive quad 4 Xs....good for 73 mph.

Any info is good info...thanks.

29scarab10

Try what you have and just spin them faster but I have a feeling you are going to need 28 quad four X (round ear).
How many rpms does your engine builder say you can turn?
Allen

knot yet

Maybe even a 27 or 28 Hydro P5-X

sommerfliesby

I've got to check on the rpms...I was thinking a 28 round-ear would be the answer as well...that's a stern-lifting prop, correct?

What would the diff between 4 and 5 blade be? Better bite on the low end for the 5?

29scarab10

Round ear propeller is typically a bow lifting prop. With the testing I have done with shorties we have never been able to get a pointed ear propeller to get on plane.
Typically
4 blade will be harder to get on plane (still pretty easy), will slip more and cruise and typically be faster on the top end. 5 blade will be easier to plane, faster cruise speed, slower on top end, and harder on drives.

What kind of speed are you realistically expecting and what gear ratio?
Allen

sommerfliesby

1:5 ratio (std Bravo). I'm looking at low to mid 80s, I would guess.

I have heard that Fountains like a stern-lifting prop? Keeps it runnnig level, which is a typical Beak-boat trait....

knot yet

Ext boxes & shorties are too going to be hard on those std bravo. Keep in mine to keep an eye out for big gear sets or xr uppers. You will need them in time.

MILD THUNDER

Mike, i have a feeling Dave will recommend propping somewhere in the neighborhood of 5400-5600 with the new motors. With the added HP, i would guess you will be able to spin your current props to around that rpm. According to the slip calculator, you had 8% slip. Thats good. if we assume 150HP additional HP, will get you an extra 600-800Rpm, and changing nothing, theoretically, you should be going around 83-84mph, turning your 26p props to around 5500rpm. The 2" shorties might increase slip, but also should increase speed from the reduced drag.

You have LOTS of props to try homie. Brian has a pair of 26 Hydromotive quad IV-X(bow lifters). You have your current props. I have a pair of Labbed 26P maximus 5 blades, lil D has 28p bravo 4 blades, and Andy has 26P bravo 4 blades.

Sooooo...get that sucker done, lets round up some props, and start prop testing! I'd really like to see you try Brian's props. I believe his will work really well.

sommerfliesby

Thinking about bringing the boat home this weekend or next...I want to really clean up the bilge and I have to pump out the old gas.

10x

Mike, first see what the #'s are on the dyno. You don't want to spin the engines any higher than you need to. See where the peak torque is and then the peak hp, then you'll have a better idea on what prop you're gonna need. Right now, you're only taking a guess.