Vibration - new Stainless prop on Mercruiser.

Howard Sterndrive

Rear Admiral
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Nov 5, 2008
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4,603
I just picked up a new Michigan Apollo XHS 4 blade stainless prop for my 92 V6 Mercruiser (50 or so hours on my SEI Gen 2 drive).
With the new prop, I have a low frequency vibration on cruise that's rumbling through the whole boat. It's not there with the aluminum 20P 4 blade (also Michigan).
I tried a new hub as I had just transferred my old hub to the new prop, but no improvement.
I initially thought it was rubbing, because even at no-wake speed there is a bit of a growl. It just gets more pronounced on plane. No evidence of rubbing though.
Is there anything else I should try before warranty?

My neighbour has a 4.3 Mercruiser in his bowrider.... thinking I'll ask if I can try it on his boat.

looks like a similar thing here:
http://forums.iboats.com/showthread.php?t=439821

same deal, I love the performance of this Apollo, but this rumble can't be doing the lower unit any good.
 

Texasmark

Supreme Mariner
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Dec 20, 2005
Messages
14,544
Re: Vibration - new Stainless prop on Mercruiser.

Where did you get the prop and do you know for sure it was in fact new. I read another thread recently where a guy like you went from a 3 to 4 and reduced vibrations. Also, since you mentioned hub, did you get the correct hub for that prop? That surely could be the problem. Since the prop is all that you changed, obviously what's wrong is new-prop related.

Mark
 

Howard Sterndrive

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Re: Vibration - new Stainless prop on Mercruiser.

prop is from iboats. it's the correct hubs I have (202).
I guess the only thing I was thinking is that the added mass of the prop was exaggerating a lower unit issue or bent propshaft, which is why I want to try it on another boat.
 

jkust

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Aug 2, 2008
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4,942
Re: Vibration - new Stainless prop on Mercruiser.

All I can say to relate is my Hustler props say to expect a bit more exhaust noise and vibration due to the exhaust holes in the prop. It's slight but I don't notice it any more since I've had all Hustlers for a few years now.. Shy of the heads up that came with the props, I'd have wondered what was wrong.
 

QC

Supreme Mariner
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Mar 22, 2005
Messages
22,783
Re: Vibration - new Stainless prop on Mercruiser.

My personal opinion is that propeller vibration, especially low speed, is waaaaaay, waaaaaaaaay, waaaaaaaaay more about differences between individual blade shape than weight imbalance. No data, no testing, nothing but WAG, buttttttt . . . If you think about the forces involved, I think weight imbalance impact is nothing compared to the forces coming off (and acting on) the blades.

Edit: I just realized, I do have data . . . Go whack one blade of your prop on something, don't whack hard enough to remove any material. Weight same, right? Guaranteed vibration ;) :D
 

Howard Sterndrive

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Nov 5, 2008
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4,603
Re: Vibration - new Stainless prop on Mercruiser.

well, I just swapped props with my neighbour - he has a Mercury High Five SS 19P.

this Apollo shakes both boats... a tiny bit less noticeable on his, but I didn't say anything much to him... he mentioned the vibration first, so it's pretty obvious.

His High Five does not vibrate on my boat, so I'm feeling better about my lower unit.
His boat has the flat trim fin and mine has a proper trim fin (notched to clear my alum 20P), but I can't see that being an issue... the SS Apollo is 14 1/8, where my aluminum is 14.25.

The only thing we didn't try is swapping thrust washers (because his is stuck on like snot to a vest), but I don't see any issue there - as nothing is rubbing.
his 5 blade may go missing one night...
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: Vibration - new Stainless prop on Mercruiser.

A new prop that vibrates is considered defective and should be returned for a refund.

This can be detected by visual inspection after mounting and running on muffs(didn't put it the water); therefore the prop is returnable.

Since you've been running around the lake with your's, not sure they will allow a return; but they should since vibration is considered a defect.
 

Tail_Gunner

Admiral
Joined
Jan 13, 2006
Messages
6,237
Re: Vibration - new Stainless prop on Mercruiser.

Call Iboats..if anything a 4 blade is actually smoother than a 3 blade.
 
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