3 blade or 4 blade prop??

I have been talking back and forth with prop manufacturers for a little bit now. They have reccomended 3 blade units for my application. I own a 95 Searay Skiray with a 250hp 5.7L Mercruiser Comp Ski. It has a 1:1 transmission.

Now after talking to a propeller dealer for the various props, they mentioned a 4 blade might be better for my application (Wakeboarding with weighted ballasts ~1500lbs).

Originally my boat comes with a 3 blade prop on it. So im wondering what you guys think I should do? This is my first time buying a prop and it seems like a really complicated decisison.

Go four blade and don't look back. It will not only increase your hole shot but will also make your boat handle better. I have a buddy with a ski ray that puts 2000lbs in the boat and he still jumps on plane. The only decision that you need to worry about is what pitch and can you go with a larger size.

def...go 4 blade it will also "feel" smoother when driving.....the wakeboard props made for wakeboard boat applications are 4 blade.

3 blade cnc prop will out perform a 4 blade

3 blade 13 x 11.5 acme

Hmm 2 sides of the spectrum

OJ reccomends a OJ XMP 3blade (Tapered Shafts), Dia: 13 inches, Cup: .090
Pitch: 11 Blades: 3 Shaft: 1" Rotation: LH

Although others are saying 4 blade.

4- way smoother and better hole shot than 3 pitch for pitch.

http://www.acmemarine.com/html/faq.html

My Sanger had a three and my Supra had a four

Sanger came out of the hole just as good if not better, and the three blade had a lot more top end.

Have you talked to Acme Props yet? They pretty much can answer any questions you might have.

I dont see how a three blade will outperform a 4 blade when it comes to hole shot and acceleration under load. Think of it this way....you are trying push X volume of water with three big blades, it will be harder for the blade and engine to push the water as each blade has to push a larger volume....but now you take an extra blade with each blade being smaller...they each have to push less water and can do it faster.....hope that makes sense. Anyone know something different?




....yes a 3 blade 13 pitch will outperform a 4 blade 14 pitch.....have to make sure your comparing apples to apples. Then there is also diameter....but as was said above with equal pitch a 4 blade will outperform. and when we talk out perform we are not talking about top end speed

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(Message edited by absoluteboarder on December 15, 2007)

General rule of thumb is that 3 blades work better on direct drives and 4 blades work better on V-drives (per the Acme prop engineer).

Three vs. four is like blonde vs. brunette. When the important thing is what shape is she in...

Look at the diameter and pitch. I would look at 882001's recommendation. Use one of the Acme 3 blade cnc props with a flatter pitch than your current prop and you should be good.

My boat came with a 4 blade, I switched to a 3 blade Acme CNC and got better hole shot, better top end, and it's smoother.
Also my fuel consumption seems to be a bit less.
Read Acmes' first paragraph on their website.

To add to Mikeski's comments on the general rule, the reason most V drives use 4 blades is because most are 1:1.5 transmissions and they normally work better for the slower spinning props. DDs use 1:1 and most perform better with 3 blades.

My V-Drive is a 1:1 - most likely why I benefited from a 3 blade

I sell a lot of props. If it were my boat, I would put on a 3-blade and pocket the extra cash. Typically, I like a pitch of less than 12" for your application.

On my site - use the discount code "Acme."

I have purchased 3 props from Karl, even returned one for exchange. Great service, great prices, Karl gets all my prop business.

My DD came stock with a 4 blade OJ, I switched to a 3 blade ACME and feel like I have gotten a performance upgrade to motor.

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I agree with the above advice, for 1:1 transmissions use a 3 blade CNC prop, for gear reduction 4 blade CNC. Karl has the reputation for great service & reasonable prices, you could do a lot worse than using him.

for the 3 blade do you think the above noted would be good for my DD application?

OJ XMP 3blade (Tapered Shafts)

Dia: 13 inches, Cup: .090
Pitch: 11 Blades: 3 Shaft: 1" Rotation: LH

Acme 525 is the prop you want. IMO superior to OJ

What Karl said... three blade CNC and spend the saved cash on sumthin else. I also buy from Karl only.