3 or 4 blade prop

[akale15]

What's the differnece/benefits between a 3 and 4 blade prop?

[Craig]

A four blade prop has one more blade than a three blade prop.

 

;-)

[A_B]

In general, the 4 blade has a better hole shot and the three blade has a better top end.

[Waternut]

I did a lot of research last year on this very topic. Typically the old school method was to get a 4 blade for better hole shot. The funny thing is, when going to a 4 blade prop you typically want to pitch the prop down because there is more drag from a 4 blade prop so automatically, you are gaining more holeshot just by pitching down but the excess drag hurts your top end.

 

With today's machined nibral props from OJ and Acme, the 3 blades are actually the best of both worlds for ski boats. The 3 blade props actually have more surface area than the 4 blade prop for better holeshot and are more efficient as well so the top end is better as well. I went from a 13x13 Federal prop to a 3 blade Acme 13x11.5 machined prop and gained substantial holeshot and picked up more speed on the top end as well....plus a slightly softer wake to cross.

 

Now 4 and 5 blade props are still the best choice for large and heavy wakeboard boats but lightly loaded ski boats stick to the 3 blade machined props and I promise you'll be very happy with your purchase.

 

You may have want to know the material differences too if you start looking so I'll touch on that. There is Nibral which is a combination of nickel, brass, and aluminum if I remember correctly. There is also stainless steel. Stainless steel used to be the best choice because it was stiff and wouldn't flex under load. The downside was, if you hit a big rock or stump, you'll destroy your entire driveline instead of just the prop. With the new machined Nibral props, the prop flexes enough to protect your driveline components but holds well enough under engine load to work just as good.

[A_B]

We used the same pitch on a 4 blade from the stock 3 blade, and tested against the reference boat, the 4 blade came out of the hole faster, but lost 1-2 mph on top end. The wake seemed softer as well. Just my experience.

 

Go fast boats run 2-blades. The fewer the blades, the greater the force thrown off each blade. At least that is what I remember reading when I was playing around with river boats. So a 3 blade in theory would be sending back a stronger force of water than a 4 blade.

 

 

[DooSPX]

I have a 4 blade OJ cnc 13.7 x 17.5 on my 1.52 powerslot as recommended by Eric from OJ. It improved my holeshot, holding speed, top end by 1mph, lowered rpm at skiing speed and lowered the bump. Eric told me that gear reduction usually perform best with 4 blades.

[ALPJr]

Me too @DooXPS. Eric OJ recommended an Oj 454 4 blade for our 92 MC 190. Lowered rpm's by 150, holds speed like a Willys in 4wd, lower and softer wake, and fuel usage improved.

[Razorskier1]

I run a powerslot tranny on my PS 197. Switched from 4 blade OJ to 2 blade Acme. Better holeshot, better top end, smoother acceleration, lower rpm while slalom skiing, and better top end by 3mph. I'd go 3 blade.

[gsm_peter]

Generic info

3 blade is cheaper to produce and repair

 

Water is very sticky and hence a 3 blade have less wet area (taken geometric impacts into consideration. A shorter hull have less resistance compared to a longer hull with exactly same wet area)

 

More blades are less impacted by drag and hence better to maintain constant speed.

 

More blades has normally larger torq and twist the boat to ride slightly more on one side.

Hence consume more gas.

 

Fewer blades gets untouched water more often than more blades.

Hence slightly better fuel consumption.

 

Larger pitch normally reduce the rpm and the engine operates in a better efficiency range.

 

I would try to find a repaired prop that is blue printed (fully balanced in all ways)

 

 

[DooSPX]

@ALPJr the same exact here. 150 rpm drop, lower bump and softer to cross, much better holeshot, better fuel economy and holding speed. What did it do to your top end? I actually gained 1 mph with the new cnc 4 blade vs the stock 3 blade, and my original 14x18 stainless 3 blade was in perfect condition.

[ForrestGump]

On the 196's, I love the Acme 470 3 blade over the Acme 422 4 blade that is stock. And everyone that skied behind the boats we used it on loved it too.

[JC McCavit]

@ShaneH - On the 196's was there a noticeable difference in rooster tail and wash behind the boat between the 3 blade 470 and 4 blade 422?

[DooSPX]

@scotchipman , that is correct, at least for me. Also correct, not a fair comparison. I have no experience with the ACME 3 blade designs. I do have a buddy who has the same boat as me with a ACME 4 blade, and to me there is NO difference between my 4 blade. (ACME did not have a 3 blade for the boat at the time).

 

Eric from OJ recommended the CNC 454 prop for me over the other props he has for that boat so that is what I got. He has found, with his current blade designs, that the 4 blades performed better over all on that gear reduction trans on that hull design. All I know is it delivered exactly what he promised.

 

They are two very different designs when you compare them, I'm sure that's the reason for the differences between 4 blade, to 3 blade between the two manufactures.

 

The main reason I chose OJ is because dealing with Eric was one of the best experiences from a personable and CS standpoint. To the point of carrying on personal convo's at times. Bill was nice on the phone, but in the end, I felt the CS and technical help was a bit better with OJ. Eric, not once, for me anyway, asked me to buy the prop no matter how many silly and redundant questions I asked with numerous phone calls.

 

One day I will like to try the new 3 blade ACME that Bill has for the 1.52 Powerslot boats, but for right now I am completely happy with my current prop. I am not saying that a 4 blade is better then a 3 blade and one company is better then the other, I am just sharing my experiences with a certain prop, from a certain company on my particular boat. That and I am very loyal to great CS. Eric has called me or texted me a few times to make sure I still like the prop and even seeing how I was doing when I was going through a pretty bad rough patch a few years ago. Just an all around great guy.

 

As far as product comparison, I feel its like Ford-Chevy, SN-MC. Both have ups and downs, take the best for what you personally want. I always tell people that I prefer OJ for the reasons listed, but I also want people to call ACME and OJ and speak with Bill and Eric and chose what fits you best.

 

 

P.S. Sorry for the long winded replay, I just hope it may help someone at sometime.

[B_S]

I have a '92 Ski Nautique, and switched from the factory 3 blade to a CNC machined 4 blade a number of years ago in order to smooth the bump at longer longs. Worked like a charm.