Prop question/help

[bstphen24]

I have a 1995 Malibu Sunsetter lx. I know not the best ski wake option, but the boat fits our family needs perfectly. Looking to upgrade from the stock prop to either the Acme 515 or 525. From my findings there is not a whole lot of difference between the two. I know the 525 is considered high altitude, we live at 3,600ft and frequent a lake at 4,500, but the guy at Acme said I would only see about 150 rpm difference between the two props. My initial thought is to get the 525 for our elevation. But have found many people saying that the 515 softened their wake. Will the 525 help with this as well? Hoping since these are fairly old props you guys have had some experience with both and can give me some insight.

[Dacon62]

Have a 515 on a 2001 Response with 325 EFI Monsoon. Very near sea level and a perfect match. At WOT it runs 4,950 rpm at 47.1 mph (GPS) with just the driver and has plenty of holeshot.

With 2 in the boat and pulling a slalom skier rpms are around 3,200-3,250 at 32 mph.

 

With your boat being a bit heavier and at higher altitude I would go with the 525. Because the 2 props are very close in size I would imagine that the wake would be similar.

 

[ALPJr]

You may want to call Eric at OJ.

[DynaSkiPete]

I'm curious about the specs of props on inboards. What are they for the two props in question? With outboards the prop is very important on a water ski boat in particular. Engine size or power along with gearing of the motor make a difference in prop selection. What is the gearing of an inboard? Are there differences for different boats? The smaller the motor on a water ski boat the more crucial the prop match to intended use. If the motor is large it is slight less concern. We usually put a 15 pitch 4 blade on a 17.6 with a 150 V-6. On a 20' model we may use the same prop or a 17 pitch or 19 pitch 4 blade. The higher the pitch the faster the top speed assuming the engine can still hit the red line.

[bstphen24]

Boat is a carbed 350 with 1:1 transmission. Mainly used for skiing and occasionally foot runs off the boom. Hoping to gain some holeshot without sacrificing to much top end.

[DynaSkiPete]

What are the prop specs? Without knowing the specifics it is hard to suggest a solution for you. You could have a prop shop tweak your existing prop to get what you want. An inch less pitch would improve hole shot without killing the top end most likely. Or they could reduce the diameter slightly. Prop shops are the experts. They are not cheap! Buying a different prop is often the cheapest and easiest solution though. Are you hitting the suggested motor red line? You don't want to exceed the suggested red line and changing the prop may allow this to happen.

[DavidN]

Go for the 525!

I’m running that exact prop on my 2010 Response CB with a 1:1 transmission and the 330hp LCR engine @ about 220ft elevation and it’s a perfect fit! (Went from the oem 515 to the 525 a few years back, still have the 515 as a spare. RPMs went up about 120. And even with the 525 I’m still not redlining @ wot.)

There will be no difference in the wake between these 2 props, however, the 525 will give you a better holeshot and better speed holding capabilities while towing a skier through the course.

 

FYI

ACME 515, 13x12, 0.8 pitch

ACME 525, 13x11.5, 0.8 pitch

[BraceMaker]

@DynaSkiPete - I probably wouldn't have someone tweak a new CNC prop - Acme and OJ both have spent time developing these props for the application and both will usually send you two props and let you compare. And both do their own repairs often for free if you buy a new prop at the same time.

Inboard ski boats were:

1:1 trans with a 1" shaft and 13x13 cast props or a 1.5:1 with a 1.125" shaft and 14x18 prop.

Its shifted now where the 1.5 was considered a bit high so most new boats are in the 1.2-1.4 range.

 

Outboards are commonly 2+:1 aren't they?

[DynaSkiPete]

The prop numbers are interesting. A difference of .5 is not a lot. Most outboard props are 2" different.

 

I'm not talking about the typical prop repair shop when I suggest having a prop improved.

 

The prop shop I'd suggest is run by guys that used to make props for a company. Props are mass produced like many boats, motors, trailers, etc. A fine tuned prop is very specific and held to much tighter tolerances than stock props are. All boat racers use these types of services. Again they are big bucks often.

 

I also know one prop company that makes over 400 different props. The owner will fine tune a prop if he likes you for free. Of course you have to be able to talk with him personally. A fine tuned stock prop is worth a couple miles per hour and often times gives a better hole shot as well. Figure paying 3 times the cost of a stock prop for the services alone. Usually one orders a stock prop from them and has them fine tune the new prop specifically for their desires. Trust me the performance prop shops are excellent. They don't like to rebuild and modify used props.

[Ski_Dad]

i have both props for my Sunsetter LXI - i like the 525 better for hole shot. Wake seems the same to me between the 515 and 525

 

You are right they run about 150 rpm apart. The 515 is 1 mph faster. It really comes down to how many people you ski with. I would really lean towards the 525. You will be shocked how much better it is than the stock 13x13 prop you probably have.

 

what is your Wide Open RPM currently ?

[Lukewarmwater]

We ran an Acme 515 on a an older Malibu ski boat(approx 1000' ASL) with carb and direct drive; it improved hole shot and smoothness significantly over the old stock prop. RPMs did not seem to be affected by more than about 50. The old prop had a 13X13-1/2 spec. There was no speed loss on the top end. Overall a big improvement. Good luck!

[Orlando76]

Go 525. If there’s any difference in wake it’d be so minor only a pro would notice. Acme are such great props out of the box.