We went with the 16x13.9 in our build. I talked with acme and they said should be a great prop and they they spent a lot of time testing it for the new Supra’s.Quote:
Originally Posted by larry_arizona
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We went with the 16x13.9 in our build. I talked with acme and they said should be a great prop and they they spent a lot of time testing it for the new Supra’s.Quote:
Originally Posted by larry_arizona
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This is no lie, my wife, I love her, has always been a little mathematically challenged. One day us and another couple who own a towboat too were chatting about how expensive these boats are filling up, how we would fill up for 150 something dollars, blah, blah,blah. Well wifey goes on her iphone and starts her calculation on how many hours and how many gallons we use, and so on, she's pecking away at her phone and then lifts her head and goes, "we use 18400$ of gas on a weekend?" We all busted out laughing and have not let her forget it since. Well, based on her calculations, if this new 5000$ prop can save 9-15% in gas, it might be worth buying it right now!Quote:
Originally Posted by larry_arizona
This is what I figured, with the odd size, it felt like an engineering project versus an off the shelf prop.Quote:
Originally Posted by smitty75
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Can someone explain how cup works? I know what it is. Lets say you have the exact same prop, but 1 has .075 cup, and the other has .150 cup. What are the results?
https://bblades.com/props-101/Quote:
Originally Posted by DNIXD99
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Yeah, I read that the other day, and still was schooled by Stazi on pitch. Which is why I am asking for clarification LOLQuote:
Originally Posted by larry_arizona
The way it was explained to me by someone at ACME was that cup mimics diameter and helps with overall efficiency. I was also told that about 0.050 of increased cup will affect your RPM the same way that increasing 1" of pitch will. I'm no expert, but I understand all this to mean that for props that are otherwise identical, the one with more cup is going to surf at a lower RPM and have a higher top speed.Quote:
Originally Posted by DNIXD99
And be more difficult to turn for the motor...they mimic each other in this way, but someQuote:
Originally Posted by mmmkay
Magical combo tends to work.
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Running at 10.8-11 mph I am only pushing about 3150-3200 rpm with the ACME 3591 (16x13.9), I haven't used another prop but based on what I've seen this is great. I pushed to 11.5 or so last time I was out and it was maybe up around 3400 or so.Quote:
Originally Posted by dakota4ce
Still loving this ACME 16x13.9 prop on a 400/1.76.
Great prop.
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Kent can you jump on plane with full ballast and 6-8 people in the boat?
Had 4 people in boat, 575# lead, 100% bow, 60/60% rear pulling a wakeboarder at 22 on plane, no problem.
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"cup" also adds surface area to the blade. Makes it a bit longer so to speak.
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How much ballast/passengers are you carry for those numbers?Quote:
Originally Posted by DDD123
I get similar RPM’s 100/100/100, 575# lead full fuel and 2 crew, 1 rider in an SA
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So all in you are around 10k on the water getting 3200 rpm....I would say perfectQuote:
Originally Posted by larry_arizona
Are you sure about that? The way Eric at OJ explained it to me is that more cup actually makes the blade react as if it were shorter while keeping the same surface area. Like a dog ear standing straight up or folded over. I asked about a new prop they had with more cup (950 and 951) and he said it was meant for a boat that was having some clearance issues.Quote:
Originally Posted by HFarr
I may be wrong about it. Not a prop designer, but if the diameter measurements are the same and it has a cup in it, it will have to have more surface area. Now if the start with a flat surface and and add cup and slightly let the O.D. shrink, then no.
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My understanding is cupping reduces the diameter a smidge and is a secondary tuning feature to further optimize pitch.
https://uploads.tapatalk-cdn.com/202...8271b2d905.jpg
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Some really good info in this thread. I knew nothing about boats, let alone props before purchasing my 2021 SA 450... I just looked and I'm running a 16 x 17 prop, which is what my dealer must have spec'ed for me. We only wakesurf, and with a lot of weight on the boat, we have struggled to get the boat to maintain autowake desired speed (say anything above 10.5mph), particularly on heavy current/wind days. I'm thinking now I should swap out my prop to a 16 x 13.9 given our use case.
I would agree, i posted in the other thread with more detail but your issue is definitely your prop. Swapping to the 13.9 will solve it.Quote:
Originally Posted by repomannv
https://www.nettleprops.com/acme-359...e-105-cup.aspx
Even a 16 x 15 will make a big difference. You would be surprised at how little bit of pitch change can go a long way on a boat prop. Just another fyi, which if you don't know anything about props at all, the first number is the overall diameter. The second number (pitch) represents how far the prop will travel through the water in one revolution. For example, your 16x17 is 16" across in size, and will move 17" forward when it make one revolution. NOW. Having said that. The 17" does not really take place because of slippage since water is not a solid object. There are a whole bunch of theory formulas with many variables to figure out what the slippage equates to. But just think about it like putting smaller or larger tires in your truck.Quote:
Originally Posted by repomannv
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Yes. This makes perfect since, and is what I was talking about with cupping adding surface area is diameter stayed exactly the same.Quote:
Originally Posted by larry_arizona
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"IF" diameter stayed exactly the same.Quote:
Originally Posted by HFarr
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ACME makes two 16 x 13.9 props, only difference appears to be cup:
#3557 which has a cup of .075"
#3591 which has a cup of .105"
The #3591 is backordered about 3 weeks right now, #3557 is available, question is, is it worth the wait for the 3591, would an operator notice the difference?
https://www.nettleprops.com/Quote:
Originally Posted by repomannv
https://www.deltaprop.com/
https://www.generalpropeller.com/acme-3591
All show in-stock. Never dealt with General Propeller but I have talked to the other 2 personally and both are willing to help you decide.
I know I keep saying it, but the 3591 was co- engineered by ACME and Supra for the 1.76 trans.
That said, not sure if you would notice the cupping difference.
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OJ props has a 16x14 that my buddy is using on his new SL, it is really nice.
Nettles is out of stock, I called. I opted for the #3591 and the wait, should be interesting to see the difference, and now I'll have a backup prop as well :)Quote:
Originally Posted by Holdmybeer
Is it possible to run the 16” prop on a 2021 moomba?
I think a 16 fits a Moomba, but I recall prop burn is possible.
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It “fits” but will definitely burn your gel.Quote:
Originally Posted by larry_arizona
Would need to install a protective plate to guard against the burn.
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Probably can just 5200 on a piece of stainless steel.
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Thanks guys, I assumed there had to be a reason they went with a 15.5" instead of the 16".
I have the Acme 3591 with.105 cupping on my 21 SL 450 with 1.76 trans. We surf with full ballast, 800lbs of lead and a small crew weighing about 520lbs. Pitch is between 9.5 and 10.5 and speed is 11.2 or 11.4 mph. Elevation is 2820ft. RPM's vary a bit due to current and chop, but pretty consistently between 3450 and 3750. I get noticeable steering wheel shake at launch, which I assume is the force of the water the prop is sending past the rudder. Anyone else experiencing this?
Also, coming off the throttle, right before neutral there is a small rattle (noise no vibration felt). No idea what this is but it is annoying me...worried there is something loose but can't see anything on the shaft and prop looks fine. Prop was refurbished and balanced. I have a second (new) 3591 that I could swap out I guess and see of that makes a difference, but maybe you all have some ideas?
Cheers!
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Are you sure your rudder is straight when you launch? I have sometimes noticed if I have it turned too far on initial launch I get a funny feeling. Lot of force hitting it on the side suddenly if it's a full throttle launch and it's (the steering wheel) turned.
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I get this with mine also, very similar setup in terms of weight, elevation, rpm's. Not so much that the steering wheel is shaking but that the rudder itself is cavitating heavily and that that cavitation is moving up the steering cable and felt, to a degree, on the steering wheel.Quote:
Originally Posted by cwfehr
In most cases the steering wheel will not be straight. You are right, if it is straight the effect is minimal relatively speaking.
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I am looking for the measurement from the middle of shaft nut to hull from a Supra so I can make a decision on running a 16in prop on my 2021 Moomba max.
If the measurements are the same or extremely close I would love to run a 16 inch prop.
I’m at 6200ft and can use all the help I can get.
Read reply #72, you can, but you'll need to install a stainless plate to prevent prop burn. Dakota has a 21 Max.... I'd run like a 15.5x12 or 15.5x12.5 on it.Quote:
Originally Posted by snowboardintahoe