G23 Prop Fell Off .....

[jfrollins]

2018 G23, 67 hours,sheared off shaft cruising at 30mph. Received boat Sept 2017

[Tallredrider]

Interesting point about no failures on the same boat twice. Also someone else observed that it seems if you get beyond 100 hours, your risk of shaft breaking goes way down.

Is Nautique the only boat mfg to use the key with a dimple? They have done this since 1997, but I wonder if this weakens the shaft to the point a 17 inch prop can then break it. Until I picked up a spare today, I had never seen one with that dimple (I've not yet swapped my own prop out).

[heel5man]

For those have issues in the 18's, which engines are you running. How about the dealer with 75% failure rate...they mostly the H6 or XR7? Also, do you know if your shaft key slot is/was shorter than what they used to be?

I noticed that my key slot is much shorter on mine this year, not extending back to the strut, unlike a friend who has a 2017 G23. I wonder if that is in effort to remediate the problem?

I have the H6, but not sure about others that experienced the failure. The GM at my dealer said he had fixed 4 this week alone.

One thing I thought was interesting... I asked him if he ever had to do a second repair on the same boat. He said so far, no, and he’s been dealing with this issue for 4-5 years. That is really puzzling to me. It would seem like the failure rate on the replacement prop would be the same unless the parts were different.


Sent from my iPhone using PLT Nautique

[ironj32]

My second prop shaft failure happened yesterday. First was on our 17 G23 and this time on the 18 G23 with mid-30s hours. We were heading home going maybe 20 mph with no ballast and four in the boat. Thankfully my buddy (also with 18 G23) was nearby to come assist, but we laughed about his shaft breaking while towing!

My dealer said his customers' failure rate was around 75% this year. They provided great service by overnighting the new shaft and will have us back on the water within 48 hours. Hope CC can get to the bottom of it soon.

For those have issues in the 18's, which engines are you running. How about the dealer with 75% failure rate...they mostly the H6 or XR7? Also, do you know if your shaft key slot is/was shorter than what they used to be?

I noticed that my key slot is much shorter on mine this year, not extending back to the strut, unlike a friend who has a 2017 G23. I wonder if that is in effort to remediate the problem?

[GMLIII]

Darn so sorry not good. Glad you will be back in action prior to the Holiday

[scottb7]

My dealer said his customers' failure rate was around 75% this year.

Wow

[heel5man]

My second prop shaft failure happened yesterday. First was on our 17 G23 and this time on the 18 G23 with mid-30s hours. We were heading home going maybe 20 mph with no ballast and four in the boat. Thankfully my buddy (also with 18 G23) was nearby to come assist, but we laughed about his shaft breaking while towing!

My dealer said his customers' failure rate was around 75% this year. They provided great service by overnighting the new shaft and will have us back on the water within 48 hours. Hope CC can get to the bottom of it soon.

[greggmck]

Agreed...where can I find a job that allows me to afford a G23 and create diagrams for PN all day? If you're hiring hit me up.

Yes. Go to great schools, get degrees in Physics and Engineering. Work for 30 years earning some of the most valuable patents, design the latest generation cloud systems and you too can retire early and surf all day with your kids. And when the water is rough you can make pictures to help others to better understand how their boats operate. So consider yourself hit up!

[fairlydangerous1]

2018 with 48 hours cracked but didn't loose prop. I shut it down just when the shudder started.

Supposedly new shafts from February 2018 are not an issue. Mine was built last year. Is it really that hard to figure out?! I don't hear this happening with other manufactures.

[dlowry81]

No wonder people don't get anything done at work .

Agreed...where can I find a job that allows me to afford a G23 and create diagrams for PN all day? If you're hiring hit me up.

[Skidave]

I have the solution:

Twin engines setup. 1) prop force load sharing. 2) redundancy if a shaft does break. 3) easier docking; thrusters not needed. 4) edge above the competition. 5) higher price [ok, this is a disadvantage for the consumer]. 6) lower ballast fill times because you already have extra weight.

We will call it the new G Squared series.

Sent from my SM-J320V using Tapatalk

[GMLIII]

No wonder people don't get anything done at work .

[Shockthis]

No wonder people don't get anything done at work .

[DealsGapCobra]

I see no reason to debate this here, the point is that there is a cyclic load on the propeller caused by differential thrust, I believe we can agree on that.

[greggmck]

It’s actually the left and right sides of the propeller that have the larger effect and I maintain boat “pitch” is a secondary issue but as we are basically discussing the same issues it doesn’t really matter. Point is there are multiple issues here and, it seems, that only the G boats have the problem. My interest is in the ways that these boat differ from everting else out there.

I think there is a misunderstanding. There is NO left and right force that can fatigue the shaft. Both the left and right blades experience the same relative waterflow and therefore generate the identical thrust. It is the top and bottom blades that cause the resulting downward force that causes the shaft to fatigue and fail. I have discussed this with several engineers very experienced in propulsion design. Perhaps you are thinking about prop torque. But prop torque causes the boat to roll to the opposite side of the prop rotation. This force is directly longitudinal to the shaft. It does not cause ANY asymmetric force that would fatigue the shaft.

Here is a picture to help one understand the issue. Both boat pitch and shaft angle combine to cause the top blades to become more PARALLEL to the water flow, reducing the relative pitch and thrust of the top blades. While the bottom blades become more perpendicular to the waterflow enabling them to generate much greater thrust than the top blades.