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new prop sizing


SJRwake

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So I have a 2001 Sunsetter VLX with what I believe currently has a stock 15" brass 4 blade prop(not sure the pitch). My question is about upgrading the prop to a larger diameter. I know all the new VLX's and MXZ's have a 17-18" prop. I am wanting to get the most amount of torque for out-of-the-whole shot and slow speed riding(for wakesurfing). Can I upgrade to a larger prop and if so what pitch?

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I"m certain you or someone else has already upgraded it.  Your model came with a 13.5" diameter prop as stock.  You'll want to make sure you don't go too large, as you'll get prop burn on the gelcoat near the tips of the blade on your hull.  IIRC, .75" is the recommended minimum distance to avoid it, but I could be wrong.

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You can usually read the prop model number, diameter, and pitch on the aft end of the prop hub.  Might have to remove the nut.

Acme 1235 is tried and true for the early VLX and LSV models.

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Your boat came with the Acme 381 stock, which is 13.5".  15.5" is as big as you can fit and not a lot of options at that diameter.

Look at the prop and see what model number is on it.  You may need a different pitch.

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So it i was wanting to get a 15.5" then, what models do they have for that and what pitch would be good? Does a lower pitch give more torque? 

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12 hours ago, SJRwake said:

So it i was wanting to get a 15.5" then, what models do they have for that and what pitch would be good? Does a lower pitch give more torque? 

Just get a 15".  You won't see a benefit of a 15.5 on your boat, selection is much more limited and cost will likely be higher.  

Here is the prop guide I created a while ago.

 

Edited by Nitrousbird
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On 12/12/2019 at 6:01 AM, Nitrousbird said:

Your boat came with the Acme 381 stock, which is 13.5".  15.5" is as big as you can fit and not a lot of options at that diameter.

Look at the prop and see what model number is on it.  You may need a different pitch.

So i looked at the prop today and found out what it is. It is the original Acme 537 that the boat came with off the assembly line, cant believe its lasted all these years. So its a 13.5"x16" 1-1/8 left. I can reach a top speed of about 50 with it but i don't care for top end. I will probably go with ACME 2921 4 Blade 15.5" x 12.5". And you are sure that I can't fit a 16" diameter?

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You can figure it out by measuring from the prop shaft to the gelcoat.  General rule is you need at least 3/4" or you will get prop burn.  Keep in mind that going up in diameter will sway the pitch a bit, meaning 12.5" of pitch with a 13" prop is effectively less than 12.5" of pitch with your 15.5" prop due to the increased surface area. 

If you're very surf-centric then I'd go with 10-11" of pitch.  Last I saw, many were very happy with the 2419 (15" x 12" x .075 cup), but if you don't think that's aggressive enough then I'd take a look at the 2949 (15"x 11" x .105 cup) or 2951 (15" x 10.5" x .105 cup).  Call the guys at ACME and see if they have a loaner or new prop to test...can't hurt to ask.  They were very helpful on the phone when I talked to them.

For point of reference:

 

 

Edited by formulaben
added link
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10 hours ago, formulaben said:

You can figure it out by measuring from the prop shaft to the gelcoat.  General rule is you need at least 3/4" or you will get prop burn.  Keep in mind that going up in diameter will sway the pitch a bit, meaning 12.5" of pitch with a 13" prop is effectively less than 12.5" of pitch with your 15.5" prop due to the increased surface area. 

If you're very surf-centric then I'd go with 10-11" of pitch.  Last I saw, many were very happy with the 2419 (15" x 12" x .075 cup), but if you don't think that's aggressive enough then I'd take a look at the 2949 (15"x 11" x .105 cup) or 2951 (15" x 10.5" x .105 cup).  Call the guys at ACME and see if they have a loaner or new prop to test...can't hurt to ask.  They were very helpful on the phone when I talked to them.

For point of reference:

 

 

thank you so much for this, i didnt even see options for anything less that 12.5 pitch. So what does bore and hub represent? And as for my understanding of it, "cup" represents the thickness of the blades is that correct?

It looks like there really are not very many options for 15.5 props or even 16" props. I guess I'll have to go with a 15" prop then.

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3 hours ago, greybeaver said:

you may want to talk to the folks at Acme as they actually know props and how they work.  They can can explain cup too!

 

May save you time and money.

Or Eric at ojprops.com  He's great.

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That thing will jump out of the water with a 15x12 on it.  Like when you put your truck in low range and forget about it.  I can't imagine needing anything pitched lower than that.  My dad has that boat with the factory 381 on it.  I'm 250 lbs and the 13.5x17.5 yanks me out of the water with aplomb and surfs with wedge down and about 2000 lbs of weight at a scant and fuel efficient 2300 RPM all day.

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21 hours ago, SJRwake said:

So i looked at the prop today and found out what it is. It is the original Acme 537 that the boat came with off the assembly line, cant believe its lasted all these years. So its a 13.5"x16" 1-1/8 left. I can reach a top speed of about 50 with it but i don't care for top end. I will probably go with ACME 2921 4 Blade 15.5" x 12.5". And you are sure that I can't fit a 16" diameter?

Have you decided from whom you will be purchasing the prop from? Your best best is to call Nettles Prop. Give them your boat year, model, and engine. Where you live (altitude makes a huge difference). What activities you will be performing behind boat and how much weight you are pushing. They hooked me up with my boat and no issues for me pushing 5000# of ballast ;)

As others have stated.. you can't just throw any size prop on there.. too close to gel and it will burn through.. friction causes heat and water compressing is a lot of heat.

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1 hour ago, kerpluxal said:

Have you decided from whom you will be purchasing the prop from?

If you go direct to the prop mfgs. they can tweak the prop for you.  Prices are very close to the volume dealers.

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Thanks for all the help everyone, So based on my engine and hull it looks like I'm gana be getting a 15" diameter with a 10.5" pitch and pobaby a .105 cup. I normally run the boat loaded with people, fuel, and ballast equivalent to 5,500lbs+ then the weight of the boat alone; so as you can tell the engine is pushing it to move all the weight at low speeds. My question is what hub length am I needing and how do I know. I will call Acme as yall suggested for more info too.

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1 hour ago, SJRwake said:

Thanks for all the help everyone, So based on my engine and hull it looks like I'm gana be getting a 15" diameter with a 10.5" pitch and pobaby a .105 cup. I normally run the boat loaded with people, fuel, and ballast equivalent to 5,500lbs+ then the weight of the boat alone; so as you can tell the engine is pushing it to move all the weight at low speeds. My question is what hub length am I needing and how do I know. I will call Acme as yall suggested for more info too.

That is way overkill on the prop and you will hate it.  I'm running similar weight and the same hull and don't need nearly that much prop (I'm guessing you have the Monsoon motor, so down on power a little vs the LS1).  My small lake prop is a 2775 and that's overkill; my big lake (and favorite prop) is the 2249, which does everything pretty well.

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I respectfully disagree, as he suggested he doesn't want to "do everything well", but instead has suggested he is surf-centric.  Although I am at nearly 3000' altitude, the 2249 is essentially the same as my 1235, but with more surface area.  Given my experience with that prop, I doubt that's what he's looking for.  You say the 2775 (15" x 12.5" x .075 cup) is "overkill" but you're comparing different engines/torque curves and perhaps decidedly difference goals.  I am of the opinion that the 2419 (15" x 12" x .075) is the least aggressive of his available choices (nearly the same as the 2775) and as posted above numerous members have excitedly praised its performance.  If you're sure that it's the wrong choice, I'd ask you to explain exactly why the 2775 (or even the 2419) is overkill in anecdotal terms so that the OP can make a determination if that is truly applicable towards his goals or not.

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9 hours ago, Nitrousbird said:

That is way overkill on the prop and you will hate it.  I'm running similar weight and the same hull and don't need nearly that much prop (I'm guessing you have the Monsoon motor, so down on power a little vs the LS1).  My small lake prop is a 2775 and that's overkill; my big lake (and favorite prop) is the 2249, which does everything pretty well.

Curious as to why you refer to a "small lake prop and a big lake prop". What performance differences are you looking for on small vs. big lakes?

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9 hours ago, formulaben said:

I respectfully disagree, as he suggested he doesn't want to "do everything well", but instead has suggested he is surf-centric.  Although I am at nearly 3000' altitude, the 2249 is essentially the same as my 1235, but with more surface area.  Given my experience with that prop, I doubt that's what he's looking for.  You say the 2775 (15" x 12.5" x .075 cup) is "overkill" but you're comparing different engines/torque curves and perhaps decidedly difference goals.  I am of the opinion that the 2419 (15" x 12" x .075) is the least aggressive of his available choices (nearly the same as the 2775) and as posted above numerous members have excitedly praised its performance.  If you're sure that it's the wrong choice, I'd ask you to explain exactly why the 2775 (or even the 2419) is overkill in anecdotal terms so that the OP can make a determination if that is truly applicable towards his goals or not.

Key word “5500 lbs equivalent” ,  need 2419 or oj945 or as you said the 2775 for that load,  my 2315 could surf that but might be at its limits even for Surf and no way for wakeboarding .    With 2419/945 there is no guessing and it’s fuel efficient under that load

Edited by granddaddy55
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22 hours ago, formulaben said:

I respectfully disagree, as he suggested he doesn't want to "do everything well", but instead has suggested he is surf-centric.  Although I am at nearly 3000' altitude, the 2249 is essentially the same as my 1235, but with more surface area.  Given my experience with that prop, I doubt that's what he's looking for.  You say the 2775 (15" x 12.5" x .075 cup) is "overkill" but you're comparing different engines/torque curves and perhaps decidedly difference goals.  I am of the opinion that the 2419 (15" x 12" x .075) is the least aggressive of his available choices (nearly the same as the 2775) and as posted above numerous members have excitedly praised its performance.  If you're sure that it's the wrong choice, I'd ask you to explain exactly why the 2775 (or even the 2419) is overkill in anecdotal terms so that the OP can make a determination if that is truly applicable towards his goals or not.

I have plenty of power in reserve for surfing, fully loaded up, on the 2249.  Even with a smaller engine, a size down should make up for the difference.  Remember, same hull and I'm running 3400lbs of ballast not including passengers, gear and the number of extra's I've added over stock on this boat (plus floating wedge).  So it is overkill as in you have more pulling power than necessary for this hull to surf easily.  I don't really save any fuel running my 2775 even on our small local lake where cruising is a non-factor.  So where is the benefit?  IMO, the OP would be best suited, assuming the Monsoon engine and caring mainly about pulling power, the 2313 at most.  Even then, still overkill.

Remember, this is a 21', 93" beam hull.  These same old Monsoon GEN-I SBC is powering 20-teen 23LSV's sacked the heck out - THOSE need the additional aggressive props, simply because the boat is heavier, more surface area on the water AND holds more ballast.  Sacked out to sacked out, it is a few thousand pound difference with more drag.  Not an insignificant difference.

13 hours ago, jmack said:

Curious as to why you refer to a "small lake prop and a big lake prop". What performance differences are you looking for on small vs. big lakes?

Small lake = don't care about cruising or cruising speed at all, as it's fill the ballast and go right off the no wake zone and aren't really traveling to get anywhere.  I happened upon the 2775 by chance (had the next one up, the 2773, but it was damaged beyond repair and had to get this one in a hurry) but I'd love to swap the 2775 with someone for something less aggressive.  Any time I go to a bigger lake, the 2249 goes on.  I keep the 2775 on because I have damaged props at our local lake before, so if I'm going to damage one, might as well be that one.  I had originally hoped the more aggressive would make it easier on fuel at surf speeds; no difference - not that my boat really sucks the fuel all that badly.

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2 hours ago, Nitrousbird said:

I have plenty of power in reserve for surfing, fully loaded up, on the 2249.  Even with a smaller engine, a size down should make up for the difference.  Remember, same hull and I'm running 3400lbs of ballast not including passengers, gear and the number of extra's I've added over stock on this boat (plus floating wedge).  So it is overkill as in you have more pulling power than necessary for this hull to surf easily.  I don't really save any fuel running my 2775 even on our small local lake where cruising is a non-factor.  So where is the benefit?  IMO, the OP would be best suited, assuming the Monsoon engine and caring mainly about pulling power, the 2313 at most.  Even then, still overkill.

Remember, this is a 21', 93" beam hull.  These same old Monsoon GEN-I SBC is powering 20-teen 23LSV's sacked the heck out - THOSE need the additional aggressive props, simply because the boat is heavier, more surface area on the water AND holds more ballast.  Sacked out to sacked out, it is a few thousand pound difference with more drag.  Not an insignificant difference.

Small lake = don't care about cruising or cruising speed at all, as it's fill the ballast and go right off the no wake zone and aren't really traveling to get anywhere.  I happened upon the 2775 by chance (had the next one up, the 2773, but it was damaged beyond repair and had to get this one in a hurry) but I'd love to swap the 2775 with someone for something less aggressive.  Any time I go to a bigger lake, the 2249 goes on.  I keep the 2775 on because I have damaged props at our local lake before, so if I'm going to damage one, might as well be that one.  I had originally hoped the more aggressive would make it easier on fuel at surf speeds; no difference - not that my boat really sucks the fuel all that badly.

You make a great point about the hull size of the sunsetter vs the hull of the new lsv's. they are deeper, wider and molded to drag and channel water better for creating a monster wave vs our old diamond style hulls. No matter how much weight i add to my boat, it will never be like the new ones simply cause of the hull pushing through the water.  

I appreciate everyone's input on this and i hope not to cause any arguments here. As I said, I am currently running the factory Acme 537 which is actually a little bit beat up too. So ANYTHING I get from here will be an upgrade for sure.

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So I talked with a technician from ACME props about my boat and size prop I'm running. We talked about my weight, and engine/vdrive. He is concerned that if I move from a 13.5" diameter prop to a 15" with so much weight that the indmar might have difficulty moving a 15" through the water and thus I'll actually loose performance. Anyone have further ideas/ experience on a 15" prop?

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39 minutes ago, SJRwake said:

So I talked with a technician from ACME props about my boat and size prop I'm running. We talked about my weight, and engine/vdrive. He is concerned that if I move from a 13.5" diameter prop to a 15" with so much weight that the indmar might have difficulty moving a 15" through the water and thus I'll actually loose performance. Anyone have further ideas/ experience on a 15" prop?

Another example of why I personally wouldn't contact Acme for suggestions.  They come up with BS like this.  Magically, because your boat came with a 13.5" prop, there is concern moving a 15".  But the same motor and same ratio Vdrive in a much larger 23LSV 10 years newer, with the same motor, they will recommend a 15" prop.  

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@Nitrousbird is spot on.  On my ‘10 23 LSV w/ 350 Monsoon it came with the 537 and it was a dog in that application unless all you did was cruise. I switched to the 1235, 14.5 x 14.25 and I could not of been happier. Surfed at 3250rpms with full MLS max wedge and with an additional 1800lbs of ballast and suck gate. Cruised at 25 mph @ 3200 rpms. Wakeboard with max MLS and wedge at 19 mph @ 3450 rpm IIRC. You can safely get a 14.5 on that hull with some safe space and not loose that much performance from a 15”. JM2C

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