Guys,

Have the lucky "opportunity" to select new props due to losing a prop shaft and prop running over the weekend in our river. Anyone have some first hand knowledge, not just a give this a try opinion?

Here's the scoop on the set-up:

1999 35' Fountain
HP500s warmed slightly ~590-600hp
Bravo drives with -2" Bravo SHop shorties
Was spinning 30P Bravos labbed by BBlades

Perf was:
Fall, cool weather [email protected] gps
Hot, humid summer ~5-5100rpm@76-78ish

Looking to get slip numbers down as they seem pretty high. Also open to buying/labbing a set of props rather than replacing the 30P Bravo LH I lost in the river. If Bravos seem to be the ticket from everyones consensus, guess I will need to get on the horn to BBlades and get a matched set...

Also, Hydros usually came on these boats... any sense in going back that direction? I believe I have seen a lot of discussion on P5's and P5X's... any comments there?

Thanks for all the great suggestions and great knowledge on this site!

razor1115

razor, We have similar set-ups and HP's (We have extension boxes vs. your shorties) When we upgraded our engines I bought a pair of P5's (29s) The stern lift was incredible, but no faster than the 29 QIV's we had labbed... around 88mph@ 5300rpms. We ended up getting 31p CNC 5blades from Julie @ Throttle-UP. Top end is around 90 @ 5300 rpms, but the big increase was picking up 10 mph midrange (76 vs 66 @ 4500rpms) The 5 blades reduced a ton of excess slippage.

I believe that if we were looking for top end gains only, I would have gone for bigger QIV's (rec labbed 32's)
I decided that I liked being able to get on plane without tabs or a struggle, over a couple mph on top.

Hope this is helpful, I have all of our testing data from a number of props that I got from Julie @ TU.
Carder

WOW Carder! 88mph rocks on 29QIV's... would be a good start and labbing should pick up 200rpm and 1-2 mph, correct? Is that possible to hit close to 90mph with just those changes? Then again, 31P CNC 5 blades might be the ticket...who is the manufacturer? Hyrdomotive?

So the extension boxes helped your boat? Can you get all the trim you need, or are you limited by the swim platform?

What was your slip throughout all your trials and frustrations?

Thanks for also reminding me about TU and their great work!

razor1115

Also, should I go ahead and upgrade to 1 1/4" shaft? Does it fit all the standard bravo internals in my -2" shorty without changes (ie just the splined dia. of the prop shaft that is external to the bearings, seals, and bullet housing)?

razor, the 29QIV's where hitting my rev limiter @ 5600rpms, with an inch of unused throttle left... that's when we calculated that labbed 32's QIV's would be about right.
The stellings boxes were factory-installed at Fountain when the boat was set up. I can trim to 5.5. The limiter stops me there, and yes, that is due to the swim platform. I don't think I need anymore trim, though.
2. the CNC's were made at Throttle-UP.
3.I wish I would have upgraded to the 1.25" shafts, but out of money by the time I replaced the engines, drive gears, and props. I believe it is a simple upgrade, using basically the same internals up to the shafts.

Our boats get a lot of prop slip,... nature of the beast.
The five blades really rock on for getting on plane, and midrange accelleration. The labbed 4 blades are still probably the fastest top end for our single step hulls...

Get some demos from Brett or Julie, or Tom @ hydromotive, (not sure what their particular programs are these days...)

If we were keeping the boat, I would be interested in some different lowers, per Monstaa's advice, as the B1's lose their effiency around 90mph. SSM's, IMCO's, or just shorities like yours.
Carder

I agree with Carder, great difference with Imco -2 shorties vs the standard Bravo lowers.

I never tried a labbed Bravo, but I did try standard Quad 1Vs - couldn't get on plane. 5 blades get with program in a hurry.

it would seem your speed is off sufficiently. slip sounds high. typically the surface pierceing shorty is effective after the 90 mark due to density changes in water. when going to shroties before that mark you usually loose the ability to carry the bow and up your slip due to the meteor effect of the long bulette. if you can i would try standard lowers. or get your hands on 1 and 2" spacers.
as an example a 36 gladiator with 700 hp, merc shorties and labbed 30 4 bld merc wheels with a 1:36 ratio ,ran 111. thats more than 20 mph difference. the glad bottom is not as efficient.
by lowering your x and usung your exhisting wheels, from what it sounds you should pick up, probably 5 by not needing to trim as much which looses speed, and carry the bow better. and lower your slip.
if your able to surpass the 90 mark i would say a 29 herring 6 bld without the extended hub. the short hub hurts plaining slightly, very slightly, but increases the mid range acceleration.
the P5's are good props, the x's tend to make the boat dnce a little as do the P6's.
for all around performance the maximus works best especially for those who chose to go long distances.
for the top end herrings.
and in some scenarios 4 bld labed bravo's.

good luck.

Monstaaa,

Great reply! So, given what you have said, what are the changes needed to install 1" spacers? I would assume it entails a different length vertical shaft as well (come with the kit)?

razor1115

Great prop information, Monstaaa. I would like to try the Herrings, since I'm looking for top speed, but there is no trial program. Do you think that I would pick up any speed over a labbed P5X?

the spacer should have orings, spacer for vertical shaft oring retainer, studs, spacer itself, and a splined coupler.