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I just had my 2007 Beneteau 323 bottom painted and my Kiwi prop lubricated and painted. I noticed that they spray painted the prop with a non ablative grey paint. I had not had the prop spray painted before. I took the boat out the next day and found that at rpms above 2000, the shaft starts shuddering a lot. Before the boat was hauled out it never did this. I'm wondering if the shuddering is a result of spray painting the prop. Each of the blades can freely rotate and if the paint on one of the blades is preventing movement, then I think this might be causing the problem (or paint drips on one blade). Has anyone else had this problem with a Kiwi prop?

Thanks

Paul
 

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the grey paint is most likley a zinc prop paint like https://www.amazon.com/Pettit-Zinc-Coat-Barnacle-Barrier/dp/B000N9RR86

Its pretty common around here for bronze props to be painted with that zinc spray paint. Im not familiar with Kiwi props and dont know what material they are made of but I gather its a folding/fetherering prop. If you are experiencing vibrations I'd consider the mechanisim itself before the paint. although I imagne that the spray paint could have gummed the mechanism if carelessly applied.
 

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the grey paint is most likley a zinc prop paint like https://www.amazon.com/Pettit-Zinc-Coat-Barnacle-Barrier/dp/B000N9RR86

Its pretty common around here for bronze props to be painted with that zinc spray paint. Im not familiar with Kiwi props and dont know what material they are made of but I gather its a folding/fetherering prop. If you are experiencing vibrations I'd consider the mechanisim itself before the paint. although I imagne that the spray paint could have gummed the mechanism if carelessly applied.
The Kiwi prop is a feathering prop and is made of stainless steel and has Dupont Zytel blades that are replaceable. There was no vibration caused by the prop before the prop was painted.
 

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Sounds like a good time to put on the dive mask and make sure the KiwiProp can move through its full range of motion. Was this not checked on the hard?
 

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bell ringer
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so the thinking is that the paint made the prop so unbalanced that it is now vibrating, but that growth on it never did


NOT
 

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so the thinking is that the paint made the prop so unbalanced that it is now vibrating, but that growth on it never did


NOT
Since painting the prop seems to have been the last change made, I think it makes sense to start looking there. He can argue with you later about probabilities... ;)
 

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bell ringer
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Since painting the prop seems to have been the last change made, I think it makes sense to start looking there. He can argue with you later about probabilities... ;)
I see you are from the non engineer side of guessing stuff
 

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I see you are from the non engineer side of guessing stuff
I don't need an engineering degree to know that when something stops working immediately after it's been changed, the odds are good the change caused the problem. Therefore, that's the place to look first. It's a rule of thumb that holds true for everything from lawn mowers to Windows programs; it usually takes little time or effort to confirm or clear the change as the culprit; and starting there is hardly the same thing as simply 'guessing.'
 

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I don't need an engineering degree to know that when something stops working immediately after it's been changed, the odds are good the change caused the problem. Therefore, that's the place to look first. It's a rule of thumb that holds true for everything from lawn mowers to Windows programs; it usually takes little time or effort to confirm or clear the change as the culprit; and starting there is hardly the same thing as simply 'guessing.'
Well said.
 

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bell ringer
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Two “people” that somehow believe a layer of spray paint can cause a boats propulsion drivetrain to become so unbalanced that it makes the boat shake, are engaged in the wag world.

Sorry
 

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Two “people” that somehow believe a layer of spray paint can cause a boats propulsion drivetrain to become so unbalanced that it makes the boat shake, are engaged in the wag world.

Sorry
I'm trying to mind my manners Don, but you aren't helping. Perhaps you need to work on your reading comprehension? Here's what the OP said:
I took the boat out the next day and found that at rpms above 2000, the shaft starts shuddering a lot. Before the boat was hauled out it never did this. I'm wondering if the shuddering is a result of spray painting the prop. Each of the blades can freely rotate and if the paint on one of the blades is preventing movement, then I think this might be causing the problem (or paint drips on one blade).
That's hardly the same thing as suggesting a layer of spray paint on a prop has unbalanced the drivetrain so badly it makes the boat shake...

I'm not familiar with Kiwi props, but I can imagine a scenario where paint in a joint could be binding one blade, thereby throwing the prop out of balance. Or maybe a painter bent one of the blades... or maybe a lot of things. But the prop's the obvious place to start looking for the problem.

If you believe the OP should ignore the prop, and go looking elsewhere instead for a problem that appeared immediately after the prop was messed with, I really don't know what to tell you.
 

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Two “people” that somehow believe a layer of spray paint can cause a boats propulsion drivetrain to become so unbalanced that it makes the boat shake, are engaged in the wag world.

Sorry
Have you considered the possibility of over spray causing one of the blades to not fully deploy causing an imbalance? While he indicates it was checked before launch it only takes a few degrees to cause the imbalance and vibration. Only takes a few drops of paint.

Whatever the cause we will know shortly as he is hauling the boat.
 

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Considering that the blades are made of a relatively light weight material that does not corrode, the effect of paint on the blades could be significantly more than the effect on similar blades made out bronze. Rotational inertia is the product of mass and distance from the axis squared, so uneven paint at the tips could have a disproportionate effect on the balance of the prop.

From the Kiwiprop website:

"NB: Ensure there are no paint runs on the blade – in particular near the sharp leading edge that can cause serious vibration problems. "

Antifouling paint
 

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Considering that the blades are made of a relatively light weight material that does not corrode, the effect of paint on the blades could be significantly more than the effect on similar blades made out bronze. Rotational inertia is the product of mass and distance from the axis squared, so uneven paint at the tips could have a disproportionate effect on the balance of the prop.

From the Kiwiprop website:

"NB: Ensure there are no paint runs on the blade – in particular near the sharp leading edge that can cause serious vibration problems. "

Antifouling paint
Well done chicory. Your investigation backs up what MAY be an issue that the lighter weight blades of the KiwiProp are prone too. Excess paint on blades causing an imbalance.

An engineer would have checked their website like you did.
 

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It’s bull.
I guess we will find out soon enough. A true engineer would have collected data from the manufacturers website before attacking those that believe the first place you look is the last thing that was changed?

Oh wait.. Wouldn't a true engineer do the same thing?

Now just go back outside Don and yell "Get off my lawn!".
 

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bell ringer
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you guys crack me up, ..................................... almost

btw an english major would first read what I acturally wrote about the paint, but a literal arts person would wonder about if it was air related and what the props political thoughts are, while the art major would wonder if the paint was the wrong color.
 

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Talk about a pissing match.
 
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