Mad Mac

Well here is the setup
38 SCARAB 9600lbs with 1/4 fuel cap.
Power-583CID 950HP X 2
Drives- SSM #5s with 2"+ spacers

Boat will run 104 at 5900 bouncing on 6Gs I never really wana run it that hard but it will go there. Did I also mention this is a no step hull!!!!!

I am running 32-18-18 4 BLADE Mercury Racing Cleavers now the boat runs well at crusing speed and all that no dissapointment she'll run 70-75 @ 4500rpm its great....the suck part is getting outta the hole....big ass turd. I cannot stay on plane much under 30mph that could present a problem getting into ruff seas. I cannot pull the engines down on rpm with these props at all they're on the rev limiters even with the drives as deep as they will go and that presents bow steer and sucky top speed.

So I know I need at least a deeper pitch but what about going to a 5 blade and staying with the current pitch. I am maxed out on diameter.

I want to be able to calm the engines down and also get some bottom end push not just prop slip. I'm having to run the engines up to nearly 5 Gs to get the boat rollin, as soon as she breaks over and planes the boat will drop back to 3200rpm and I am running right at 58 mph in what seems to be seconds.

Ive tried deeper pitch 4 blade but different rake so I didnt see much bottom end gain. Its exspencive to toss around race props so I would like to get theoretical thoughts first.

racinfever

Try some 31pitch 5 blades

A.O. Razor

+1

Give Bblades a call and get some test props. 17.5"x31" 5 blades or 17x31" 6 blades would be the ones I would try.

Mad Mac

I am going to contact a gentalmen here in the clasiffieds about some 5 blade 31 pitch 18 Dia. I;m also calling BBlades in the afternoon only s***ty part is the boat is in layup now so I have to wait 6 months to try it

bbladesprops

I would try some 17x32 / 17x34 5 blade props.
We have them for testing.

(By the way, Mercury never made a 4 blade #5 cleaver at 18 degrees of rake. Only 15 degrees.)

Call us and we can discuss options or call when your ready to test again and we'll get you taken care of.

Brett

MILD THUNDER

iTrader: (3)

I have found on my setup (SSM IVs Mounted high) that it is very sensitive to props. For example. Ran a set of 18x28 3 blades. Not to bad to plane, a bit of blowing out, but pretty much bring to 3500 and it will lay over. Then tried 16.75x28 four blades. Would not plane whatsoever. Then went to a 17x29 4 blade, took forever but would plane eventually. Then tried 16.5x28 5 blades. Planing was excellent, but did not care for the handling. Finally tried a set of 17x27 labbed 4 blades. Planes like a ski boat. No blowing out, hooks up and goes.

What i suppose I am saying is, that it seems as if the old ssm props are not very cut and dry. All these props I tried were merc props. I am no prop guy, but I did notice the 17x27 props had quite a bit more cupping than the others. Maybe thats the ticket.

Mad Mac

My drives are High but I run a 2 inch spacer to get them down a touch, are you running spacers at all? I never get any blow out.

MILD THUNDER

iTrader: (3)

You said you have to bring the engines to 5k rpm, to get rolling, then they drop to 3200 and it planes. That's what I consider blowing out.

No spacers on mine, but that's irrelevant since we are talking two totally different setups. Cupping in a ssm prop can be the difference in a un-useable prop to a great one.

Awesome boat you have. Was drooling over it for a while when it was for sale! Those speeds are awesome for a straight bottom 38!

Mad Mac

I ment blowing out at speed sorry, yes it blows out right at 3 grand when I am trying to get it on plane. if I feather the crap out of it I can kinda keep it mild but it takes so long I get impatiaent and push the sticks.

adk61

iTrader: (5)

if you push the sticks you're gonna cook the trannys... better get a hold of your issue cause transmissions aren't cheap!!