G23 Transmission Noise Under Load (Normal or Not?)

[Jbertram1245]

Hi all,
I wanted to reach out to the community regarding what may or may not be an issue with our 2020 G23. At the end of the season last year we began to notice a pronounced noise coming from the transmission on the boat. It is most notable when the boat is fully loaded and we are accelerating to wakeboard speed. In the video I have attached we are accelerating from a stop to 23 mph with full ballast. If you listen close it sounds like there is an irregular whirl that is very loud and pronounced. We had the dealer look at the boat and try to diagnose the issue, but they were adamant that everything was in working order, even after a test drive.

If this is a noise others experience I would greatly appreciate a response. Maybe someone else has experienced something similar and knows what the issue is? If there is an issue I would like to have it fixed before the warranty expires on the boat. We do a lot of wakeboarding and almost every new person I’ve had on the boat has commented on the abnormal noise we are hearing. I am almost positive this sound was not there during the first 3 summers of operation. I have attached a video via a google drive link. If anyone has trouble accessing the video please let me know, I would greatly appreciate any advice or experience to help me figure out what is going on.

Thank you All!

Boat Info
2020 G23
Engine - ZZ6 450 DI
Standard Ballast
Typically only 3-4 people in the boat

[NautiqueJeff]

Sounds like something is out of balance somewhere. I can tell you that the boats I have had over the years didn't make that particular noise.

[BasaltRMK]

Jbertram1245 - watched (and listened to) the video a couple of times. Are you referring to the high-pitched whining noise, or the background ,wah-wah-wah' noise? I ask because we have intermittent transmission noise that the dealer can't seem to figure out (2020 G21, ZZ-6). When we're weighted and we accelerate SLOWLY from a stop or idle speed, we sometimes get this weird 'wah-wah-wah' harmonic sounds that does not go away until we stop. However, if we accelerate QUICKLY from stop/idle, we don't get the noise. It's not a prop issue, it happens using different props.

Is this anything like what you're seeing, or is your issue that high-pitched whine?

To the hive mind, any and all input welcome.

Good luck!

- bob

[Jbertram1245]

NautiqueJeff Thank you for the input, I agree it sounds like something is out of balance. I have a feeling its transmission related because the sound is most notable right below the rear seat where you can see the transmission rotating at the end of the V drive.

[Jbertram1245]

BasaltRMK I am referring to the (wah-wah-wah) wasn't sure how to describe the sound but you hit the nail on the head lol. The sound is extremely noticeable when getting on plane at full ballast and you can slightly hear it when you accelerate empty. But anytime there is any load on the motor that (wah-wah-wah) noise is persistent. It seems to be getting noisier as the season continues which is concerning. Would hate to run into a big issue prior to peak season. I appreciate the input! Does that sound always occur when you're under load? or just occasionally from a stop accelerating slowly?

[BasaltRMK]

It's intermittent. Doesn't always happen when accelerating slowly, but ONLY happens when accelerating slowly. It has even occurred when accelerating slowly with no ballast. But we mostly notice it when ballasted cause we're always ballasted

If we 'drop the hammer' it never happens.

In our case, we've had the issue since we owned the boat, and we ask the dealer about it every off-season when the boat is in for service. They have no ideas, but I think they're just running the boat in the shop on a fake-lake so of course they can't replicate it. I was hoping they'd find something when they did the 300-hour service with the v-drive and transmission inspections and fluid changes, but no luck. We're stumped, and like you I'm nervous that it will turn into something more serious about the time the warranty is up, or crater a season.

I'll keep you updated with my issue, please do the same.

Thanks,

- bob

[Jbertram1245]

BasaltRMK Ours makes that noise under slow acceleration and when we drop the hammer, unfortunately. Our dealer said the same exact thing, they could not replicate the issue. I doubt they actually had the boat in the water. We had our driveline inspection last fall and they didn't find anything abnormal. I wonder if this is just a characteristic of the zz6 or maybe the transmission? I hope our two experiences are not isolated. The dealer has not been very helpful in identifying a solution. Would be interesting to hear if anyone else has experienced the same issue.
Thanks for the feedback I will keep you updated as well!
-Jack

[jpwhit]

The "wah wah wah" sound is characteristic of a Resonance Vibration. It's the same phenomenon that took down the Tacoma Narrows Bridge.

https://www.youtube.com/watch?v=j-zczJXSxnw

The "wah wah wah" is just the audio expression of what caused the Tacoma Narrows Bridge to gallop and ultimately collapse. It something that just about every engineering student studies in school if you take advanced civil or mechanical engineering classes. It's important for engineers to understand the Resonance and Natural frequency of structures they design, and how that will interact with other frequencies involved in the system. In this case it's likely the Natural Frequency of the boat hull/structure is close enough to the engine vibration frequency that a Resonance occurs.

The reason it's a required topic in many engineering disciplines, is because bad things tend to happen when this occurs. The way you fix it is very easy from a theoretical point of view. You need to modify the Natural Frequency of the boat hull / structure. You do that by adding bracing and other stiffening or actually removing stiffness. But figuring out where to do that is the hard part in practice. It's typically done with pretty advanced modeling software.

[Jbertram1245]

jpwhit very interesting. Was not aware of such a phenomenon. So what you’re saying is that there is not anything wrong mechanically, but it’s just the nature of the hull? Have you come across this previously with the g hull? Just want to make sure I’m interpreting your response correctly.
thanks for the reply!
-Jack

[jpwhit]

No, nothing wrong mechanically. On the scale of a boat, there is likely no real negative consequence to this other than potentially being slightly annoying.

[Scooter G]

I wonder if this recent post is of similar nature, although a wah wah is a little different from a squeal I would suppose...

https://www.planetnautique.com/vb5/f...loud-squealing

I had to think about this more a few minutes, but if Jeff is calling it out as not normal, and the boat is still under warranty, I would want it fixed. When you take the next owner for a test drive (along with everyone else that rides in the boat), and they say, what the heck is that noise?
New Trans, V-Drive, I don't care, make it go away...

[jpwhit]

I wonder if this recent post is of similar nature, although a wah wah is a little different from a squeal I would suppose...

https://www.planetnautique.com/vb5/f...loud-squealing

I think any similarity stops at both of these being "noises". The 2nd one is a kind of noise that IMO can only be diagnosed in person. Not the kind of issue where a forum can be much of any help.

[BasaltRMK]

Scooter G - Definitely very different noises, but I agree with your overall premise; I want it properly diagnosed and addressed by a trained Nautique mechanic. Given that in my case it's intermittent, it seems like something is not right.

Thanks,

- bob

[ffmedic74]

I had a similar issue and ended up being a bad V drive covered under warranty.

[Jbertram1245]

ffmedic74 Thank you for your input. I was really hoping it would be a simple fix but it would make sense that something is internally not right in the v-drive. Any idea how long it took the dealer to get the V-drive? I'm wondering if this is something we will have to deal with this season and have repaired over the winter. I imagine it would not be a simple process.
Thanks again for the advice!