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View Full Version : 3-blade vs 4-blade prop for slalom skiing?


markcr
04-06-2010, 11:12 AM
Looking for advice from any knowledgeable slalom skiers out there who can explain the noticed difference in wake shape, hump, etc. between a 3-blade and 4-blade prop. I'm not concerned with boat performance and hole shot. With today's prop technology, either prop can get my skinny butt out of the water with no problem. I'm mostly interested in the props affect on the actual slalom wake.

Kevin 89MC
04-06-2010, 11:26 AM
Looking for advice from any knowledgeable slalom skiers out there who can explain the noticed difference in wake shape, hump, etc. between a 3-blade and 4-blade prop. I'm not concerned with boat performance and hole shot. With today's prop technology, either prop can get my skinny butt out of the water with no problem. I'm mostly interested in the props affect on the actual slalom wake.

I'll jump in. Note: My comparison is between an "old school" 3 blade and an "old school" 4 blade on my '89 PS. I have not skied behind one of them new-fangled CNC jobs yet, so keep that in mind when evaluating. When I switched from my 3 blade to my 4 blade, I noticed a slightly better hole shot, not that I needed it, as even my old 240 HP direct drive pulls me up plenty good with the driver going easy on the throttle. I may have lost a little on the top end, but I wasn't doing much footing back then so I can't say for sure.
The one thing I did notice is that the "rooster tail" or prop hump, whatever you want to call it, was a fair amount smaller, or at least flatter, with the 4 blade. I put the 3 blade back on a few years ago, and realized that the 22 off bump was bigger with the 3 blade. Not horrible, but noticeable beyond just imagining it (at least I think so) :)
My bro in law's '98 came with a 4 blade, and he stuck on my 3 blade to see if he could gain any top end, and he didn't. I think he was just footing, so he didn't comment on the rooster tail change on his.
Good luck, and try both on your boat if you can. What year boat do you have? I would guess the hull design also has an effect on the differences between a 3 and 4 blade.
Kevin

east tx skier
04-06-2010, 11:48 AM
I don't have a link handy, but BrianM did a prop comparison between an acme 3 blade and a couple of OJ's, one of which I believe was a 4 blade. Might have some good info in there for you.

ahhudgins
04-06-2010, 02:04 PM
I changed from my stock 3 blade to an OJ 4 blade on a 89 PS190, and my 95 Maristar 200. I saw no difference in either rooster tail. My friends and family are purely recreational skiers, we do a little bit of everything. I mostly wakeboard, barefoot, and a little trick ski (nothing fancy). I may have put the slalom ski on twice last year, and I saw no issue with the rooster tail at 34 MPH long time. Same with barefooting at 41 MPH.

Maybe some of the hard core, short line, slalom skiers can give more input. Besides the quicker, smoother hole shot, I do find that the speed is a LOT easier to keep steady and adjust with the 4 blade.

ahhudgins
04-06-2010, 02:08 PM
One more thing. When I was first interested in the 4 blade, my MC dealer let me try one of his used ones before I bought mine. I'm not sure if OJ or anyone of the prop manufacturers offer a "try before you buy" deal?

EJ OJPROP
04-06-2010, 02:15 PM
OJ instituted the "Try Before You Buy" program. I'd be happy to send a prop for a trial. It is best for you decide which prop works for your needs.

broncotw
04-06-2010, 02:19 PM
OK I am interested in this topic.... I own a 1985 Prostar Stars and Stripes (351W) with the 1:1 Tranny.... Currently it has the OEM 3 bladed prop...... Would I get better performance and hole shot with a 4 bladed prop? What would this do to my top end? What are some recommended 4 bladed props to include brand and pitch?

Thanks,

EJ OJPROP
04-06-2010, 02:26 PM
13 X 13 LC 1" OJ FORCE 4-blade would be a good place to start. May lose 1-2 MPH on the top end.

russlars
04-06-2010, 02:40 PM
OJ instituted the "Try Before You Buy" program. I'd be happy to send a prop for a trial. It is best for you decide which prop works for your needs.
I would definitely take up Eric on his offer to try a few props and see how they work for your boat at the line length you like to ski at, etc. I did this last year when I was trying to improve my ski wake and even though the differences are subtle I really liked the wake with the 4 blade OJ 12.5 X 12 CNC prop. With this prop I sacrifice a little bit of performance, but the wake improvement is worth it to me. I will also add that I tested 2 ACME props as well and currently run a 3 blade ACME 541 prop part of the time. The ACME is a great performing prop but puts out a little bigger bump at the line length I like to ski at. Hope that helps.

ahhudgins
04-06-2010, 03:12 PM
13 X 13 LC 1" OJ FORCE 4-blade would be a good place to start. May lose 1-2 MPH on the top end.

He could always wax the bottom of the hull and pick up that extra 1-2 MPH!! Naa, just kidding. I've been very pleased with the OJ 4 blade on my Maristar. I may have lost the 1-2 MPH but I never barefoot above 41 so it's not an issue for me. The hole shot, constant speed, and smoothness far out weigh the 1 MPH loss in my situation.

93Prostar190
04-06-2010, 06:13 PM
On my previous boat a 93 PS 190 with Powerslot, I changed from a 3 blade to an OJ 4 blade 14x18 prop and I thought the wake became softer and with less "foam" to it ..... that is definitely just a gut feel but myself and 3 other skiers made observations about it.

It definitely pulled like a freight train and I don't think we lost more than 1.5 MPH on the top end like most people report. Driving seemed a little bit better at holding speed as well.

That was before the CNC props ..... the OJ 4 blade was sweet on that boat.

My current PS 214 has the newer OJ 3 blade that is stock from the factory, but with the MCX engine, I have not yet decided if switching to the 4 blade on this boat will be in my future.

BrianM
04-06-2010, 06:15 PM
Here is the link to the comparison I did last year. I prefer the 3 blades for my application but your mileage may very.

http://www.mastercraft.com/teamtalk/showthread.php?t=31670&highlight=prop

flya750
04-06-2010, 08:44 PM
The 4 blade will be quieter in the turns.... I didn't notice any other performance differences.

BrianM
04-07-2010, 08:58 AM
The 4 blade will be quieter in the turns.... I didn't notice any other performance differences.

Not necessarily true. I found the 4 blade to be noisy on my boat.

DooSPX
04-07-2010, 10:45 AM
As soon as I get the funds, I am going to get a OJ #454 CNC four blade on my 91 PS190 Powerslot. I figured a prop is the best bang for the buck rather than upgrading heads and intake on the 240hp.

DooSPX
04-30-2010, 10:33 AM
Not necessarily true. I found the 4 blade to be noisy on my boat.

I spoke with Eric about that... he told me that there are so many factors on why it was like that. Mostly the wrong prop for the hull/engine/trans combo could be the big factor.

FoggyNogginz
04-30-2010, 06:15 PM
I have been through this several times myself, and I find that sometimes this will vary for two models of the same boat (which is really puzzling). Both OJ and ACME have try & buy and/or will accept returns. I am an ACME fan because they have been far more responsive when I called or emailed, but your luck may vary here as well.

I was running a four blade OJ, and switched to a 3blade ACME because the 3 blade CNC is actually more efficient with more surface area. My opinion (everybody has one), is that the three blade offered a softer propwash for slalom, but the four blade was better for wakesurfing because the wake was smoother closer to the boat for whatever reason.

The thing that few folks discuss is rake and this also has a huge bearing on your application. A prop with more aft rake raises the bow, and may cause additional porpoising at WOT. For this reason, I just switched back to a four blade with less rake this week because the three blade rake raised the bow a bit too much and caused additional porpoising at high speeds.

With all of the variables involved, you really have to consider what is more important to you: Slalom wake, surf wake, wakeboarding, hole shot, and/or WOT? This is commonly a little bit of give/take in one area or another, so my sugestion is to call one the prop manufacturers and have a good discussion on you are looking for in a prop. Then be pepared to try two or three if necessary to find your maximum grin.

Good luck!