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props and wakes


usaski1
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So, I'm sure this has been discussed to death somewhere... but I got to thinking about my prop tonight, a 3 blade 13x? (not sure, and couldnt tell when I wnt out and looked) question is, how big of a differnce does the prop make on wake size? I havent read much, but seems like 3 blades cause a larger, maybe sharper wake, and might not be as smooth.. thinking of switching out to 4 blade.. not sure if it will make a large difference. My goal is to alter the wake size (make it smaller) and perhaps make the whole boat smoother...
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Keep in mind that the hull bottom profile will dictate what comes out the back wake wise.

Now different prop blade profiles will lift or drop the back of the boat while underway hence causing percieved wake changes. Big differences between Prop manufacturers and their products, Acme's tend to be rather ineficent slip wise where as an OJ will have far less slip. If one wants a quick pickup and quicker accleration a ACME is the best product as it will alow the engine to run up into it's power range quicker and come to speed to some degree a bit faster over it's counter part. Want a propeller that will hold speed and run top end faster a OJ is a better choice. We have been running The OJ 13X15.5 four blade on our 6 liter 200. For our application in slalom it seems to not make the speed control feel like it is running away from us as did the ACME. Also the Trick table is cleaned up, For jump The OJ holds speed into the base well just does not have the recovery from the load as quick as the ACME does. Again these comments are baised on our findings and our prefernces of our boat set up.

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@ usaski1 Yes mine was both. (OJ 4 force) Not huge, but certainly noticeable. Only downside was the opposite to Eltorro's experience, at trick speeds we got a small double ripple off the wake, but it is minor. That's the difference in boats. We mainly slalom so I would never go back..
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JP how is everything in Mont? Cold and wet as usual? I grew up on the west side of the divide in the Flathead Valley Charter member of the Echo lake water-ski club (defunct except for few of us old guy's)

If you are satisfied with your current performance prop have some cup taken out it will pep things up a little. What prop do you currently have on your boat? what elevation do you run?

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El Torro is Stephen Seal I told him he had to start putting back into the sport and he had to start with BOS!

 

Ed: Yes very noticeable difference in RPM, our 200 with the OJ will run right at 3680 with a short line 34 mph skier and two people in the boat. the ACME ran over 3900 with the same load. one of the biggest benefits to me and as I use the the setup is that the boat does not feel like it wants to run away from me at the buoy with the ZO speed control. That has been one of my complaints about ZO. My thoughts on this set up is that I have mechanically dumb-ed the system by utilizing the power band of the engine in the lower RPM range. Hence throttle response is slower yet RPMS and or speed is less likely affected because of the lesser RPMS and less slippage of the OJ wheel. The OJ wheel On the boat feels firmer off the ball but the boat remains more constant through out the slalom process, We also don't hear the motor rev oscillation working like we did with the ACME. Again this is what I have found with my own personal boat and have also been able to repeat the set up on other owners boats with very favorable results and feed back by the boat owners and their skiers.

I have urged Eric at OJ to come up with a prop for the 200 5.7 package but at this time their is not a prop from OJ that will make that package work like what we can do with the 6 liters. another thing we see is far more 16.95 and 16.08 rather than a lot of .94 and .07 that we saw with the ACME. so I believe we have come up with a formula that seems to soften up the ZO Zoom!

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My boat is a 2000 Ski Nautique and had a 4-blade OJ prop. I tested the the 3-blade acme and 4-blade acme. My goal was to lower my overall rpms. The 3-blade had a better holeshot than both 4-blades. But the trade off was hull noise/vibration. The acme 4-blade was smooth as silk and lowered my rpm @ 34mph by 200 rpm.
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@jody seal Somehow I already knew that you and Eric Lee were Montanans - I think it's because of your world-conquering ways! Or maybe Greg Alsbury told me... while we were skiing Echo Lake! I'm pretty familiar with Kalispell. My Great Uncle Ben owned a bar in Hungry Horse when I was a wee lad, and my grandpa had a ranch just on the other side of Glacier, and we used to spend every Christmas at Big Mountain suffering the fog!

 

Anyway. I have the stock three bladed prop on the boat now, so I may follow yer advice and save some dough. We're at about 4600' here in Bozeman, but my boat skis at sea level at least once a year when we vacation in the Seattle area.

 

Look me up anytime you find yourself back in God's country!

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I've tried various three and four blade Acmes over the years. I couldn't tell a difference in vibration between them. Three blade was best all around on my 93 Hydrodyne. Actually got a better hole shot and higher top end with the 3 blade than the four. I have a 4 blade 422 on my 02 SN 196.
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Jipster, I have the same boat and have been looking to lower and soften the wake to. USA ski, Sounds like the oj 4 blade would be the best choice, call Eric their. Any body got any other ideas? After much investigating I believe the transom of most the older MC'S run low in the water which must be a direct reflection of the wake and terrible chine spray at short ropes. I think Im going to add a wake\trim tab to the center rear of the transom next. Everything I have read and heard this should help get the transom up some. Many other Tourney boats have used them before so why not. MC in the early 2000's even added a hook to the transoms to do this same thing. I rather not do a permanent modification, bolt on is easier and adjustable.
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jefflyman, I put an aluminum plate/angle on my Response a few years ago when we had some water issues for one season. Because I didn't want anything permanent, I just bolted it through the drain plug hole. Just kept trimming it and changing the angle/plate until the wake was back where I wanted it.
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jefflyman My plate had a vertical leg mounted to the transom and a horizontal leg about 9" wide and 4-5" long. I didn't measure the angle, but I'm guessing about 2-3 deg downward tilt compared to the hull bottom. I took off the drain plug fitting in the centre bottom of the transom and mounted the vertical part of my plate flush with the transom. I put a large bolt through the drain hole and also used the 3 small screw holes that were there from removing the drain plug fitting. I just needed a little lift. I only used it for the one season because our water is now back to normal. There are no left over signs that it was ever there.
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jipster43, jefflyman, Whats up guys, it's Jason (DooSPX) from TeamTalk. I feel you need to call Eric from OJ, he will set you up. I know the CNC XMP 4 blade OJ 13.7x17.5 .110 cup on my Powerslot, made a HUGE difference in every way. with my 240hp, it has MUCH better holeshot, actually gained a tiny bit of top end, holds speed like a vice- even with my hardest pull, and softened the wake and bump too. Plus Eric will let you try before you buy. I cannot say enough about Eric or my prop. Stand up guy, answered all my stupid repetitive questions and we shot the sh** too.
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Doo, thats a huge prop for that power. It must work though. I have talked to Eric email only. He suggested the exact prop I've been useing! Im working with Bennett tabs to have one built. Looks like it will be 14" long the tansom x about 11"inches off the back hydralic adjustable. We ski with 1 to 5 people in the boat so adjustabilty should be a great option. Hopeing to lose some wake is the main goal and NO headers this summer!
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Jeff, it works for sure... my stock prop is a OJ stainless 14x18 because of my powerslot transmission. It felt like I gained 40hp out of the hole, and I gained about a my top end, and my stock stainless was in excellent shape too.

 

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Hey Doo! Thanks for the prop knowledge! I'm going to try Jody's recommendation and have some cup taken out of the prop. I'm satisfied with the wakes, but I'd like a little more holeshot to satisfy my ego and curb my tendency to covet thy neighbor's Powerslot!

 

On a side note it was 50 degrees here in Bozeman today. Should be able to break ice and install bouys soon!!!

 

JP :)

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This is a good time to ask this question, why would anyone need more hole shot??? With our 285 hp we never use full throttle to get me (200lbs) up or anyone else. It was 5 years ago the first time getting up behind my new to me MC I heard a loud snap noise. Thinking I ripped a vest buckle I finished skiing that run. That night in much pain I knew I did something bad. Next day after xrays I torn many ligements in my chest! Done skiing for half the summer, sucked. SO...... why the need for that hole shot?
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I'm 5'11" 195lbs. & own a 96 prostar w/ the 275 HP TBI motor & stock 13X13 prop. I don't need any more holeshot, never did,as far as holding speed I'm working on the green loop so I don't think it really matters.

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