400 with 1.76 transmission prop choices

[larry_arizona]

I know the prop options in 2020 for the 400/1.76 was a 16x17 and 16x15, looks like there is a new option 16x13.9

Anyone running the ACME 3591 16x13.9? Sounds like an absolute stump puller.


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[Cactus371]

I know the prop options in 2020 for the 400/1.76 was a 16x17 and 16x15, looks like there is a new option 16x13.9

Anyone running the ACME 3591 16x13.9? Sounds like an absolute stump puller.


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That’s what I’m running on my SE


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[SONIC]

I run the 16x15 on my 400 with 1.76 and it does fine fully loaded and tops out at 38.

The 13.9 assuming the same prop slip would only drop the top speed to 35 and would likely be significantly torquier down low.
Seems like a good option to me.

[larry_arizona]

35 top speed is plenty, I will order the 16x13.9

The fastest I go is wakeboard speeds 22-23mph


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[Shoebox]

I know the prop options in 2020 for the 400/1.76 was a 16x17 and 16x15, looks like there is a new option 16x13.9

Anyone running the ACME 3591 16x13.9? Sounds like an absolute stump puller.


Sent from my iPhone using TapatalkI have the 16x15, and have considered trying the 16x17. There are no issues launching, but the rpms are a little higher at surf and wakeboard speeds. Anything taller would be nuts.

[larry_arizona]

I have the 16x15, and have considered trying the 16x17. There are no issues launching, but the rpms are a little higher at surf and wakeboard speeds. Anything taller would be nuts.

What RPM does the 16x15 give at wake and surf speeds?


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[Shoebox]

What RPM does the 16x15 give at wake and surf speeds?


Sent from my iPhone using TapatalkFull ballast surfing 11.2-11.4 I'm about 3700-3800 rpm, with lead and maybe a little water ballast at 22 is about the same. I do have the 450 though.

[SONIC]

@Shoebox what's your drive ratio?

I'm 1.76 : 1 and run about 3200-3400 at surf speed on the 16x15 prop full ballast

[Stazi]

That’s nice and low for Rpm’s


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[larry_arizona]

@Shoebox what's your drive ratio?

I'm 1.76 : 1 and run about 3200-3400 at surf speed on the 16x15 prop full ballast

Curious how much RPM would increase with the 16x13.9?


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[Stazi]

Probably +8% all round if slip I the same.


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[SONIC]

The prop calculator I use is showing about 200-250 rpm increase with the same slip.

[Stazi]

That’s 8%. [emoji851]


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[SONIC]

Pretty much yep :D

[Shoebox]

@Shoebox what's your drive ratio?

I'm 1.76 : 1 and run about 3200-3400 at surf speed on the 16x15 prop full ballast1.76. I also have 1k lead.

[larry_arizona]

I would be happy surfing at 3600rpm with a 16x13.9

Do you have the prop slip calculator?


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[SONIC]

https://www.rbbi.com/folders/prop/propcalc.htm

Here you go, good to play around with.

[DNIXD99]

I thought lower Pitch was supposed to produce lower RPM, and lower Top Speed.

[DDNorCal]

I was just up at Tahoe with 3k of people and lead and running 3800 rpm at 11.4.

[Isaguel]

I would think the 16x15 would be sufficient. I run the 16x17 now and all 100% full ballast+ 500 lbs lead distributed evenly side to side + crew of 4-5 adults and I have not experienced any lag pulling a surfer. 400 engine. I thought it would be necessary to go down to 16x15 but have not been hurting for it. I do plan to get a second prop and it'll be 16x15 but frankly, not out of necessity. Just my 2 cents.
I just cant imagine what I'm gaining by moving down to a 13"pitch. Loose speed, increased RPM. Considering how my boat handles it now, I just don't see the payoff for what I'd be giving up.

[larry_arizona]

Supra no longer offers the 16x15.

Choices are
Standard 16x17
Optional 16x13.9, 16x12.5

My dealer recommends the 16x13.9, 80% take rate.


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[Stazi]

I thought lower Pitch was supposed to produce lower RPM, and lower Top Speed.

No. It will produce a lower speed at the same rpm as before, but more torque/thrust. So if you have a top engine speed of 5000rpm, your top speed will be lower at that rpm the it was was with a higher pitched prop.


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[dakota4ce]

Supra no longer offers the 16x15.

Choices are
Standard 16x17
Optional 16x13.9, 16x12.5

My dealer recommends the 16x13.9, 80% take rate.


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The 16x13.9 sounds weird AF—must have a lot of cup to make up for the pitch. Any idea what cup is?


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[DNIXD99]

No. It will produce a lower speed at the same rpm as before, but more torque/thrust. So if you have a top engine speed of 5000rpm, your top speed will be lower at that rpm the it was was with a higher pitched prop.


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Well that makes sense then. I guess my 2943 (10.5 pitch) was operating properly. I had more torque, but higher RPMs at the same surf speed. I see a lot of people doing the exact same thing, and expecting lower RPMs at the same surf speed. I went back to my 2419 (12 pitch). It has just enough power for my setup, and runs about 300-500 less RPMs. Ideally, I think Id want an 11.5, but Acme doesnt sell it. Thanks for the clarification. It makes sense.

[larry_arizona]

The 16x13.9 sounds weird AF—must have a lot of cup to make up for the pitch. Any idea what cup is?


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Cup is .105”

Here is the link:
https://acmemarine.com/products/acme-3591-16-00-x-13-90-4-blade


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[dakota4ce]

Cup is .105”

Here is the link:
https://acmemarine.com/products/acme-3591-16-00-x-13-90-4-blade


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Seem to remember that .025 cup sort of acts like 1” of pitch, or at least can. This makes sense if my recall is on.


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[larry_arizona]

Seem to remember that .025 cup sort of acts like 1” of pitch, or at least can. This makes sense if my recall is on.


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Seems like someone designed a very specific prop..... perhaps SC custom designed this prop for the 1.76 trans? The 13.9 is a very specific pitch.

It appears to have replaced the 16x15 prop option.


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[dakota4ce]

Seems like someone designed a very specific prop..... perhaps SC custom designed this prop for the 1.76 trans? The 13.9 is a very specific pitch.

It appears to have replaced the 16x15 prop option.


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I did just chat with Jim at Acme two days ago and he did not mention it. Oddly enough. And I called specifically to discuss 16 X 15.


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[larry_arizona]

I did just chat with Jim at Acme two days ago and he did not mention it. Oddly enough. And I called specifically to discuss 16 X 15.


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To clarify, SC no longer offers the 16x15 option, at least not on the Supras.


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[dakota4ce]

To clarify, SC no longer offers the 16x15 option, at least not on the Supras.


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Moombas are all OJ props from the factory. Always strikes me as peculiar. The factory 15.5x16.5 may be just fine, too.


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[SONIC]

I guess people were still looking for a bit more from the 16x15 so they dropped it to the 16x13.9 (agreed odd number there, they are usually in increments of .25)

I'd go that route personally, when I need a spare I'll probably grab one.

[dakota4ce]

I guess people were still looking for a bit more from the 16x15 so they dropped it to the 16x13.9 (agreed odd number there, they are usually in increments of .25)

I'd go that route personally, when I need a spare I'll probably grab one.

Except is has enough more cup to act like the 15” in a basic sense. It must offer an advantage for hooking up better.


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[dakota4ce]

I ran my 16x15 heavy as a MF in my SL and it was plenty of grunt. 5100# of water plus 300 lead on wakeboard plane like a rocket.


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[larry_arizona]

16x13.9 with heavy cup may be more efficient than a 16x15


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[SONIC]

It's my understanding that more cup has more holding power in the water so it should hook up better with less slip out of the hole.
More cup also can increase top speed.
how the hell any of the physics work on a propeller Is over my head haha

I'm waiting on one of these to become available for the wake boat segment:
https://www.sharrowmarine.com/

[larry_arizona]

It's my understanding that more cup has more holding power in the water so it should hook up better with less slip out of the hole.
More cup also can increase top speed.
how the hell any of the physics work on a propeller Is over my head haha

I'm waiting on one of these to become available for the wake boat segment:
https://www.sharrowmarine.com/

Lol, for $5000 I will wait. Also would not run a Stainless steel prop on a V drive unless it had some form of engineered sheer pin.
https://uploads.tapatalk-cdn.com/20200812/d5ade2ee203ac3785a72e7fa2d4e0258.jpg


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[SONIC]

Lol, for $5000 I will wait. Also would not run a Stainless steel prop on a V drive unless it had some form of engineered sheer pin.
https://uploads.tapatalk-cdn.com/20200812/d5ade2ee203ac3785a72e7fa2d4e0258.jpg


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I agree it's probably still years out from being affordable but the tech is very cool and apparently it really works and reduces fuel usage and plane speed considerably which would be awesome on a wake boat. They also have videos showing it essentially eliminates cavitation at the prop edges.
if they can CNC it from stainless they can do the same from Nibral.

They started them for tankers where a 1% increase in fuel economy is millions of dollars

[mmmkay]

I was running the 3337 (16x15 with 0.075 cup) on my 2020 SL400. We run full ballast, 500 lbs of lead (all towards the back to get the nose up to about 9.5 degrees), and a crew of 6-8 adults. Had no problems surfing 11.4 mph at 3k feet of elevation (3750 RPM +/-150 at depending on load and pitch), but fully weighted on a hot day we could not plane out. We don't wakeboard so this is not usually a problem for us. But, we took the boat up to 5k feet of elevation and it could barely hold 10.0 mph fully weighted. We came prepared and pulled the boat out to put on a 3409 prop (16x13 with 0.150 cup) and it solved all of our problems! Shockingly surf RPM is exactly the same but we have more holeshot, it gets up to speed faster, is much more responsive, and if we hit a wave it can easily temporarily rev above 4k to maintain speed (something the 3337 could not do). We can even slowly plane out fully loaded at 5k feet now. I was not expecting that out of the 400 motor - thank you Supra Launch! Fuel efficiency for surfing is also slightly improved - went from averaging 7 gph to 6.5 gph. Even though it's running the same surf RPM, the motor sounds like it's not working as hard and is slightly quieter. Top speed dropped from 37 to 34 mph so fuel efficiency while cruising at 25 mph (3800 RPM vs. 4100 RPM) has gone down but it's a small price to pay for a WAY better set-up. I highly recommend the 3409 for anyone with the 400 motor and 1.76 transmisison. I was originally planning to only use this prop when we were boating at elevation but we're leaving it on all the time now. Even at 3k feet it's a noticeable difference and much better.

[SONIC]

Awesome feedback.

[larry_arizona]

I was running the 3337 (16x15 with 0.075 cup) on my 2020 SL400. We run full ballast, 500 lbs of lead (all towards the back to get the nose up to about 9.5 degrees), and a crew of 6-8 adults. Had no problems surfing 11.4 mph at 3k feet of elevation (3750 RPM +/-150 at depending on load and pitch), but fully weighted on a hot day we could not plane out. We don't wakeboard so this is not usually a problem for us. But, we took the boat up to 5k feet of elevation and it could barely hold 10.0 mph fully weighted. We came prepared and pulled the boat out to put on a 3409 prop (16x13 with 0.150 cup) and it solved all of our problems! Shockingly surf RPM is exactly the same but we have more holeshot, it gets up to speed faster, is much more responsive, and if we hit a wave it can easily temporarily rev above 4k to maintain speed (something the 3337 could not do). We can even slowly plane out fully loaded at 5k feet now. I was not expecting that out of the 400 motor - thank you Supra Launch! Fuel efficiency for surfing is also slightly improved - went from averaging 7 gph to 6.5 gph. Even though it's running the same surf RPM, the motor sounds like it's not working as hard and is slightly quieter. Top speed dropped from 37 to 34 mph so fuel efficiency while cruising at 25 mph (3800 RPM vs. 4100 RPM) has gone down but it's a small price to pay for a WAY better set-up. I highly recommend the 3409 for anyone with the 400 motor and 1.76 transmisison. I was originally planning to only use this prop when we were boating at elevation but we're leaving it on all the time now. Even at 3k feet it's a noticeable difference and much better.

This is awesome, sounds like the 16x13.9 .105 cup will be a good choice under 2000 feet


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[smitty75]

I know the prop options in 2020 for the 400/1.76 was a 16x17 and 16x15, looks like there is a new option 16x13.9

Anyone running the ACME 3591 16x13.9? Sounds like an absolute stump puller.


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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.


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[Isaguel]

Lol, for $5000 I will wait. Also would not run a Stainless steel prop on a V drive unless it had some form of engineered sheer pin.
https://uploads.tapatalk-cdn.com/20200812/d5ade2ee203ac3785a72e7fa2d4e0258.jpg


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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!

[larry_arizona]

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.


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This is what I figured, with the odd size, it felt like an engineering project versus an off the shelf prop.


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[DNIXD99]

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?

[larry_arizona]

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/


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[DNIXD99]

https://bblades.com/props-101/


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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 LOL

[mmmkay]

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?

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.

[dakota4ce]

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.

And be more difficult to turn for the motor...they mimic each other in this way, but some
Magical combo tends to work.


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[DDD123]

And be more difficult to turn for the motor...they mimic each other in this way, but some
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.

[larry_arizona]

Still loving this ACME 16x13.9 prop on a 400/1.76.

Great prop.


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[SONIC]

Kent can you jump on plane with full ballast and 6-8 people in the boat?

[larry_arizona]

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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[HFarr]

"cup" also adds surface area to the blade. Makes it a bit longer so to speak.

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[Hayden]

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.

How much ballast/passengers are you carry for those numbers?

[larry_arizona]

I get similar RPM’s 100/100/100, 575# lead full fuel and 2 crew, 1 rider in an SA


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[Holdmybeer]

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 perfect

[KnoxMojo]

"cup" also adds surface area to the blade. Makes it a bit longer so to speak.

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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.

[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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[larry_arizona]

My understanding is cupping reduces the diameter a smidge and is a secondary tuning feature to further optimize pitch.

https://uploads.tapatalk-cdn.com/20210629/3442edfe512ff55c630ff08271b2d905.jpg


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[repomannv]

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.

[SONIC]

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.
https://www.nettleprops.com/acme-3591-propeller-4-blade-16-x-13-90-lh-1-1/8-bore-105-cup.aspx

[HFarr]

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.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.

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[HFarr]

My understanding is cupping reduces the diameter a smidge and is a secondary tuning feature to further optimize pitch.

https://uploads.tapatalk-cdn.com/20210629/3442edfe512ff55c630ff08271b2d905.jpg


Sent from my iPhone using TapatalkYes. This makes perfect since, and is what I was talking about with cupping adding surface area is diameter stayed exactly the same.

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[HFarr]

Yes. This makes perfect since, and is what I was talking about with cupping adding surface area is diameter stayed exactly the same.

Sent from my moto z4 using Tapatalk"IF" diameter stayed exactly the same.

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[repomannv]

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?

[Holdmybeer]

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/

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.

[larry_arizona]

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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[KnoxMojo]

OJ props has a 16x14 that my buddy is using on his new SL, it is really nice.

[repomannv]

https://www.nettleprops.com/

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.

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 :)

[sleek98]

Is it possible to run the 16” prop on a 2021 moomba?

[larry_arizona]

I think a 16 fits a Moomba, but I recall prop burn is possible.


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[dakota4ce]

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.
Would need to install a protective plate to guard against the burn.


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[larry_arizona]

Probably can just 5200 on a piece of stainless steel.


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[sleek98]

Thanks guys, I assumed there had to be a reason they went with a 15.5" instead of the 16".

[cwfehr]

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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[HFarr]

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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[Hayden]

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?

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.

[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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[snowboardintahoe]

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.

[KnoxMojo]

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.

[snowboardintahoe]

I saw it, I am just a skeptic and want to confirm there is actually a difference in clearance. (Unless someone actually had burn in)

I have a 15.5 / 11 on it and it rips people out of the water and gets on plain very easy but when we cruise to the other side of the lake (22 miles) the 7mph loss is not awesome.

If there is a difference in clearance I will probably run 15.5/12.5 because the stock 15.5/16 couldn’t get me above 11mph loaded 12 people 1000k lead

[KnoxMojo]

Dakota put a plate on his to prevent prop burn. It will burn. 15.5x12.5 is what I'd go with for your elevation and wanting a little more cruising speed

[HFarr]

I saw it, I am just a skeptic and want to confirm there is actually a difference in clearance. (Unless someone actually had burn in)

I have a 15.5 / 11 on it and it rips people out of the water and gets on plain very easy but when we cruise to the other side of the lake (22 miles) the 7mph loss is not awesome.

If there is a difference in clearance I will probably run 15.5/12.5 because the stock 15.5/16 couldn’t get me above 11mph loaded 12 people 1000k leadWow! I have a 15.5x15 on a Makai with a 400/1.76 that runs fine with all ballast full and a crew of 12+. Of course I am only a few hundred ft above sea level.

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[Tommy2slow]

You’re first stop (and it will probably be you last) when researching a new prop should be Jim Thelen at ACME. He will ask all the right questions to get you the prop you need. I have a 15” x 13” and it is super aggressive but will still do 32 mph. I couldn’t really imagine going with anything with less pitch than that at our 2200’ lake. As far as diameter goes, Supras can, generally speaking, run a larger prop than Moomba. I measured my clearance and a 15.5” prop would not have left enough clearance on my 2020 Mojo. My boat came with the OJ that I think they call 15.5” x 16” and it was the completely wrong prop for that boat with extra ballast. It was the same diameter as the new Acme 15” prop and too much pitch for the boat. The new prop will get the boat up on plane with full ballast but I only tried it once to see what it could do. I would never run the boat like that in normal use.

Keep in mind when choosing a prop that you don’t need a prop that can get you across the lake at 35 mph with a crew of 10 and all 5000#’s of ballast full. Most members on here high idle to their favourite surfing spot while filling and only run about 50% ballast when wakeboarding. I have heard a few members comment on how happy they are with the 13.9” pitch that they are running. I suspect that it still has lots of grunt while running a little lower rpms. I have about 4800 #’s of ballast and and 1100 #’s of crew and turn about 4100 rpm at 12 mph.

That’s my two cents. I hope you find the perfect prop and please let the forum know what you pick and how it performs. The search for the elusive perfect prop is never ending.

[SONIC]

Keep in mind when choosing a prop that you don’t need a prop that can get you across the lake at 35 mph with a crew of 10 and all 5000#’s of ballast full.

But that's the dream isn't it :cool:

[snowboardintahoe]

I spoke with Jim from acme and he put me on the 15.5/11 and I should have returned it with in the 30 days but I didn’t want to pull my boat out of the water(30min each way 70$ launch fee and $7.49 a gallon and I have to tell my wife she’s doing great when she’s got the trailer on the curb)
He was very concerned about my elevation and extra weight. 15.5/13 here I come!

[HFarr]

I spoke with Jim from acme and he put me on the 15.5/11 and I should have returned it with in the 30 days but I didn’t want to pull my boat out of the water(30min each way 70$ launch fee and $7.49 a gallon and I have to tell my wife she’s doing great when she’s got the trailer on the curb)
He was very concerned about my elevation and extra weight. 15.5/13 here I come!LOL!! I have seen some of the best arguments and fussing take place at the boat ramp! Nothing makes someone madder than having to wait on a trailer to be pulled up and back over and over the same crooked way every time! LOL. Especially if there are other people waiting to use the ramp. Or the other side of the equation where the boat driver pulls up and back because they just can't hit the bunks straight. Yep. Some good yelling takes place there for sure. But, I am very fortunate in that my wife can back a trailer very well. I have even been sitting just offshore in the boat and seen her get out of my truck and go back someone else's truck and trailer down the ramp for them after watching them pull up and back several times! Gotta say it's funny to watch a man get out of his truck (which it has been a man a couple of times, but mostly other women) to let a woman back it for him. People usually cheer for her too.

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[Moombas]

I've now spoken to 3 gentlemen with Moomba Max's that run 16" prop and have been for a few years with no prop burn.

2 of them are running the ACME 3337 and one of them is running the OJ 963.

When talking to Jim over at ACME he does think a 16" prop is just going to perform better with the 1.76:1 trans.

He explained the deeper the gear ratio the more necessary and critical prop diameter, and that If I feel comfortable running a 16" prop that will be the better decision.

I am thinking of going for it, as I have not yet heard of any prop burn on the moomba Max specifically.

[larry_arizona]

A thin piece of stainless glued on to prevent any burn would be great.

I have seen that used before.


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[Dukabor]

A thin piece of stainless glued on to prevent any burn would be great.

I have seen that used before.


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I was originally concerned with prop burn when I switched to a 16”…. Ran it all last season and did not see anything on the hull… that is on a Makai of course, so I cannot speak to other models…. Nothing wrong with adding some protection if it helps you sleep better at night !

[Moombas]

Thanks for the reassurance, just spoke with Jim, 3591 inbound and sending my 3407 back because I was surfing at 4400 rpm which was awful.

Now I have talked to 4 Moomba owners that have no prop burn with 16" props.

[larry_arizona]

3591 is a great prop. Your RPM's will be much lower than 4400


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[larry_arizona]

In case anyone is looking for a deal on a 3591 prop, prop depot in Tennessee has them for $814 free shipping plus $10 code, $804


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[Moombas]

In case anyone is looking for a deal on a 3591 prop, prop depot in Tennessee has them for $814 free shipping plus $10 code, $804


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This prop rocks so far, I was able to add some lead back for a total of 800lbs of lead + my 5,500 lbs of water ballast. I am holding speed either side at around 9* pitch the wave is amazing. I can surf at 11.2-11.8 RPM always under 4,000 now. I also got the prop from ACME but ordered a 3591B (blem) for under $700. The reason I like the B props is it usually just means they were installed and tested and then returned. It also allows you to exchange them until you find the right prop.

I do think This is pretty much the edge of the weight limit for this boat with the 400 if you are trying to achieve that 9-9.5* pitch which seems to be the general consensus for the best wave. If you bring the pitch down to 8 you could run more weight no problem, but the wave won't necessarily be better.

[Dukabor]

Great to hear you are getting dialed in !!

Looking forward to getting out and finding the limit myself this year !!