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Another "G" bites the dust... (broken shaft)


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what we G owners are seeing.... unscientifically.... is that its an infant mortality rate type thing. Every single one of these has happened... somewhere around 25ish of 2600? Gs, has happend with under 80hrs on the boat. Usually in the 20-40hr range. Seems to be no trend, as its happened on the 1 1/8" shafts, the larger 1.25" shafts, G21, G23, G25... 409 up to 550s, 1:48 and 2:1 trannys. So its kinda all over the place.

In every instance reported... they've had the boat repaired and back up in under 24hrs, its a 2-3hr job. Although they wont reimburse for a tow in bill, or for dock service for those who dont have a trailer.

Edited by nyryan2001
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prevailing concensus is that is has to do with the key slot, how it was cut or tempered. They all seem to have sheared clean where the key slot ends toward the front

Prevailing consensus on PN was that, first, bigger shafts were needed, now that there is a metallurgical problem. One would think that if there was a "prevailing consensus" it would be the designers at Correct Craft and given new shafts are still snapping, doesn't appear that there is any prevailing consensus, or else something would be done about it.

Edited by 85 Barefoot
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While a number of these boats are made, they still have hand made pieces on them like the shafts. These boats are pushing a lot of weight and there probably isn't a lot of extra leeway built into these shafts. The best engineering and craftsmanship can be easily trumped by poor quality in the materials. Getting good raw billet to make parts such as this isn't as easy as it used to be.

A couple of broken shafts wouldn't prevent me from buying a G. Everyone has some problems in areas.

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Is it really a surprise? These boats weighs 1000-1300 lbs more than most, and have 3000 lbs of stock ballast. I am actually surprised we have not seen anything like this from other makers, these boats are being pushed to there limitations, WAY over the recommended CG weight placard in the boat. Not to mention the extreme load on the engines and transmissions, who knows what the longevity will be on these. A G loaded with gear, fuel, ballast, could be pushing 12k lbs of weight, pretty insane if you think about how much a Volkswagen bug weighs,.

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well thanks 85, but thats directly from the VP of Customer Service/warranty at CC. But as always, you probrably know better.

So what? Doesn't negate one thing I said. And I know nothing. And if there is in fact a "prevailing consensus" (your words) why are there still boats having issues and what is CC doing about their QC control on this since you're so in the know?

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well.. a "custom" loaded malibu, centurion... is not far away from a standard G? Or are all the G's with broken shaft filled with enzo sacks?

Anyway - worst case scenario for me - sitting on a lake and need help from another boat to get back.

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well.. a "custom" loaded malibu, centurion... is not far away from a standard G? Or are all the G's with broken shaft filled with enzo sacks?

Anyway - worst case scenario for me - sitting on a lake and need help from another boat to get back.

As long as it didn't send the prop through the bottom of the boat ;) It would be interesting to see more pictures of the total damage, I wouldn't assume that the prop was just going to fall away harmlessly if the shaft breaks right behind it.

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It all depends on how the shaft was made.

If I had to guess it was probably cast, machined, and perhaps heat treated. If that's the case, and it's snapped, then it's probably really close to its design safety factory (given the scenarios probably not), or probably cast form widely varying steel, or the steel has porosity.

I doubt it's a forged shaft.

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Is it really a surprise? These boats weighs 1000-1300 lbs more than most, and have 3000 lbs of stock ballast. I am actually surprised we have not seen anything like this from other makers, these boats are being pushed to there limitations, WAY over the recommended CG weight placard in the boat. Not to mention the extreme load on the engines and transmissions, who knows what the longevity will be on these. A G loaded with gear, fuel, ballast, could be pushing 12k lbs of weight, pretty insane if you think about how much a Volkswagen bug weighs,.

Yes, I'd say its a surprise. Correct used to make the old cuddy and fish nautiques with 1" shafts and those were BIG boats. Furthermore, the stress on these shafts should be more than handleable. Good write up by Ryan1776 on planet nautique showing the relative lack of stress on the shaft.

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Love the fact that within 10 posts on that thread,there are multiple people saying things like:

-(the OP is a) "one post troll" bashing the G with some hidden agenda"..........

-or "Yeah I am not buying this thread" ..........

or my personal favorite, by Nautiboy ...sounds fishy to me along with all the "other guys that had shafts break on them with no photos" Shafts do break, I had a 2006 SA 220 with 800 hours and the shaft broke, so I do know it happens,

Sooooo, lemme get this straight: you had a Nautique with a snapped driveshaft, and you know others have as well, but because the OP didn't post pictures within 12 hours, he's lying to make you mad? :lol: Okie dokie "Nautiboy".

But on a positive note.......those ^ reactions do help to explain a few things for me :whistle:

Furthermore, it is touted in this thread that "somewhere around 25ish" G's have had shaft issues, when there were 3 at ONE dealership as of April 2013.

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Yes, I'd say its a surprise. Correct used to make the old cuddy and fish nautiques with 1" shafts and those were BIG boats. Furthermore, the stress on these shafts should be more than handleable. Good write up by Ryan1776 on planet nautique showing the relative lack of stress on the shaft.

Did those cuddy and fish nautiques have 500+pound feet of torque and/or 2:1 transmissions with big props?

Add to that 12,000 of total mass to move at a high engine load. Doubt that 5000 pound cuddy ever came close to that much stress on the drive-train.

Edited by Tims
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So what? Doesn't negate one thing I said. And I know nothing. And if there is in fact a "prevailing consensus" (your words) why are there still boats having issues and what is CC doing about their QC control on this since you're so in the know?

Well they are honoring their boat warranty and fixing them asap. At all their dealers.....as in immediately, not refusing service because a boat wasnt bought there. VP of customer service actually returns phone calls and talks to customers to make things right. No reports yet of it happening twice on the same boat.

And to answer your question, VP said with such a small population of affected boats, they havent reached a verdict on the exact cause, when 99%+ of the boats never have an issue. He said he thinks it has to do with the key slot.

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Did those cuddy and fish nautiques have 500+pound feet of torque and/or 2:1 transmissions with big props?

They were 454s and darn big props...either way, the driveshaft can only "see" so much torque, which is limited by engine output, not raised by gearing.

Edited by 85 Barefoot
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Well they are honoring their boat warranty and fixing them asap. At all their dealers.....as in immediately, not refusing service because a boat wasnt bought there. VP of customer service actually returns phone calls and talks to customers to make things right. No reports yet of it happening twice on the same boat.

And to answer your question, VP said with such a small population of affected boats, they havent reached a verdict on the exact cause, when 99%+ of the boats never have an issue. He said he thinks it has to do with the key slot.

Good, they should for a known debilitating mechanical problem on a $130,000+ boat. But lets face it, you have no idea how "all their dealers" are handling. Posts online seem as if most are doing a great job, which is commendable.

But lets face it, inboards have used essentially the same driveshafts for 40 years +. It's a pretty big problem to have your flagship boats breaking a part that's been used for decades. Not quite the same as incorrect ballast levels on LINC.

Edited by 85 Barefoot
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They were 454s and darn big props...either way, the driveshaft can only "see" so much torque, which is limited by engine output, but raised by gearing.

True, but when you gear down these boats + run them at max/near max engine load often, the drive system is certainly going to see more stress than a fishing or cruiser boat tooling around.

The key way explanation makes good sense. Depending on how or when that key way is machined into the shaft can have a negative impact on strength. Could also explain why it happens early in the life of the shaft.

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True, but when you gear down these boats + run them at max/near max engine load often, the drive system is certainly going to see more stress than a fishing or cruiser boat tooling around.

The key way explanation makes good sense. Depending on how or when that key way is machined into the shaft can have a negative impact on strength. Could also explain why it happens early in the life of the shaft.

Point taken, but you know how big those boats were, right? they weren't no 20 foot bay boats. But I understand your point.

As to a physics analysis though, there were failures before the 2:1 and not involving the 555. If the failures were limited to those, it would be one thing, since not, seems a mechanical, design, or production issue.

Edited by 85 Barefoot
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Be interesting to see what grade of steel is being used. Most shafts are 431 stainless. Duplex SS 2205 is a jack of all trades but Aquamet 22HS is a really strong shaft with a very high tensile strength for it's diameter but harder to machine so would cost more, or there's 630 grade but it does not handle corrosion as well.

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