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Old 12-09-2015, 14:12   #1
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Vibration at > 1400 RPM

Hello everyone
I own a Beneteau 473, with which I d'like to sail around for some years. It is 12 years old and has a Volvo TMD22 and a three blade NON-folding Propeller.

At about 1400 RPM and more, there starts a noisy vibration. It is not on the Engine, more behind it. I already had a mechanican on the boat, who aligned the engine new, so that the shaft can be turned easily by hand. But the vibration are still there.

The vibrations only occurs, if the prop is turning, so no vibration in neutral even at higher RPMs.

When I dive to the Prop, everything seems to be normal. The only thing I am not sure about: it is normal that I can move the Prop and the Shaft under Water a little bit... maybe 1-2 Milimeter. Should this be tighthen? There are two plasctic-screws right behind the Prop. What are these for?

Can anyone help me?

Thank you very much!
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Old 12-09-2015, 15:48   #2
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Re: Vibration at > 1400 RPM

I can't comment directly on a B473 but in general I would say 1 or 2 millimeters of play is way too much. I would replacing the bearing when the play is half that.

The bearing is not adjustable, it has to be replaced. The screws you mentioned probably just locate the bearing or prevent it from turning in the housing.

This play may or may not be part of the vibration problem but needs addressing anyway.

What is your history with the boat and the vibration? Some background may help point to the source of the problem.

By the way, welcome aboard CF
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Old 12-09-2015, 21:47   #3
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Re: Vibration at > 1400 RPM

Replacing the cutlass bearing might cure your problem. Being able to shake the prop side to side or up and down indicates it's time to replace. A ding in the prop or some fouling would cause it to vibrate too as well as a bent shaft but my suspicion is that the cutlass bearing is the culprit in this case. You would see exceptional fouling or a bent blade.
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Old 12-09-2015, 23:45   #4
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Re: Vibration at > 1400 RPM

Quote:
Originally Posted by Peschi View Post
Hello everyone
I own a Beneteau 473, with which I d'like to sail around for some years. It is 12 years old and has a Volvo TMD22 and a three blade NON-folding Propeller.

At about 1400 RPM and more, there starts a noisy vibration. It is not on the Engine, more behind it. I already had a mechanican on the boat, who aligned the engine new, so that the shaft can be turned easily by hand. But the vibration are still there.

The vibrations only occurs, if the prop is turning, so no vibration in neutral even at higher RPMs.

When I dive to the Prop, everything seems to be normal. The only thing I am not sure about: it is normal that I can move the Prop and the Shaft under Water a little bit... maybe 1-2 Milimeter. Should this be tighthen? There are two plasctic-screws right behind the Prop. What are these for?

Can anyone help me?

Thank you very much!


cutlass bearing, check propeller, shaft coupling bolts to be tight

M.E
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Old 13-09-2015, 08:15   #5
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Re: Vibration at > 1400 RPM

Thanks a lot for your answers!
Background: I bought the boat 2 months ago and the vibration were there from the beginning.
When the boat was still out of the water, I made a Photo of the Propeller. I try to attach it here.

When I read your answers, I think I should replace this cutlass bearing. But for this, the boat has to be out of the water. It was my plan to take the boat out of the water in about one year. Do you think I have to do it earlier?

Thanks a lot!
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Old 13-09-2015, 08:23   #6
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Re: Vibration at > 1400 RPM

Quote:
Originally Posted by Peschi View Post
Thanks a lot for your answers!
Background: I bought the boat 2 months ago and the vibration were there from the beginning.
When the boat was still out of the water, I made a Photo of the Propeller. I try to attach it here.

When I read your answers, I think I should replace this cutlass bearing. But for this, the boat has to be out of the water. It was my plan to take the boat out of the water in about one year. Do you think I have to do it earlier?

Thanks a lot!
If you don't want the vibration you do....

Can be done in the water, but it ain't easy...

PS: Keep your "mechanican".... Those are hard to find!
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Old 13-09-2015, 10:14   #7
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Lightbulb Re: Vibration at > 1400 RPM

At the same time I would have the prop balance and blades checked if bent. Either can accelerate the cutlass bearing wear.
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Old 13-09-2015, 10:26   #8
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Re: Vibration at > 1400 RPM

Heres myself using a cutlass bearing removal tool under my 37 foot striker sportfish.removing the starboard cutlass bearing.It took longer to get the old one out then it did to put in the new one.20 hours underwater to remove it an 1 hour to install the new one.I found out the tool will not get a 8 inch bearing out all the way.I got 6 inches of it out and had to carve the rest out with a very sharp filet knife.My bearing was made out of plastic and rubber.

https://youtu.be/lIrhIG9mY90
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Old 13-09-2015, 11:41   #9
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Re: Vibration at > 1400 RPM

Are you speaking lateral movement or fore and aft? The assumption seems to be lateral, in which case replace the cutlass. If you pull the prop have it trued and balanced.
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Old 13-09-2015, 11:58   #10
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Re: Vibration at > 1400 RPM

Quote:
Originally Posted by Peschi View Post
Hello everyone
I own a Beneteau 473, with which I d'like to sail around for some years. It is 12 years old and has a Volvo TMD22 and a three blade NON-folding Propeller.

At about 1400 RPM and more, there starts a noisy vibration. It is not on the Engine, more behind it. I already had a mechanican on the boat, who aligned the engine new, so that the shaft can be turned easily by hand. But the vibration are still there.

The vibrations only occurs, if the prop is turning, so no vibration in neutral even at higher RPMs.

When I dive to the Prop, everything seems to be normal. The only thing I am not sure about: it is normal that I can move the Prop and the Shaft under Water a little bit... maybe 1-2 Milimeter. Should this be tighthen? There are two plasctic-screws right behind the Prop. What are these for?

Can anyone help me?

Thank you very much!
Hi Peschi,

Welcome to the forum.

We had a similar vibration last year and planed to replace the cutlass bearing this spring as we knew it had a small amount of play. [an unmeasured 1.5-2mm]

We also double-checked engine alignment, drive shaft coupling, shaft runout, propeller fouling and balance, shaft zincs for tightness (about 1/4 consumed at inspection time.) etc. All were spot on, so the probable culprit was still the cutlass bearing.

Weather postponed our yard appointment this spring, so we had a diver do a quick check, clean the prop (after sitting all winter in the slip) and replace the 2 shaft zincs. So far we have motored over 120 hours this season, and we have experienced no vibration at any RPM.

While we still plan to replace the cutlass, I have to attribute the vibration from last season to the 2 zincs as they are the only change since last year. The replaced zincs were only about 1/3rd consumed, and the diver didn't think either were loose. [I should mention our shaft is 45mm (1.75") so our shaft zincs are pretty hefty at a little over a kilogram (2.2 pounds) each.]

The lesson learned is sometimes the simple things contribute to these issues.

Good luck solving your issue.

By-the-way, do avail yourself of the excellent articles at Compass Marine when it comes time to replace your cutlass.

Cheers!

Bill

[Edit] Addendum: Since I posted I had your photo come through (slow cell data today...] so obviously shaft zincs are not contributing to your situation. When you change your cutlass bearing, I would also recommend sending your prop to a good shop for truing and balance check.

I'll try to attach a photo of our prop and shaft zincs for reference, below.

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Old 13-09-2015, 12:06   #11
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Re: Vibration at > 1400 RPM

I'm not sure about your original statement regarding alignment of the engine and drive train. Did your mechanic do this since your purchase of the boat? If not, I would start there. One mm of shaft slop within the cutlass bearing is not good, but not not awfully bad. Two mm is getting bad, so comments regarding replacement of the bearing are appropriate if that is accurate. You can do the shaft to engine alignment in the water, but replacement of the cutlass bearing is best done out of the water. I have been able to do that within an hour or two, and not require repainting of the bottom.
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Old 13-09-2015, 12:10   #12
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Re: Vibration at > 1400 RPM

Quote:
Originally Posted by Cadence View Post
Are you speaking lateral movement or fore and aft? The assumption seems to be lateral, in which case replace the cutlass. If you pull the prop have it trued and balanced.
if you can move it fore and aft then it's inside the reverse gear, or a loose coupling. check to see if there is lateral movement at the coupling....without the engine running. are you leaking oil at the output shaft on the reverse gear? if so replace the bearing and seal.

Side to side movemnet is the cuttless. check that the shaft is true as that can cause the bearing to ware. with no strut on the shaft your mechanic should have seen a bent shaft if he aligned it the right way. in which case he would have rotated the shaft a few times during the alignment whilst rechecking the gap. Before tightening the coupling.

Pulling the shaft and bearing can be done in the water. if you are doing it yourself you can save money and spend time if you hire someone to pull it underwater it might cost close to or as much as hauling out. in that case I'd haul out. you can do a better job on the hill.
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Old 13-09-2015, 13:10   #13
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Re: Vibration at > 1400 RPM

If you want to check one other thing that can be done while in the water that could cause the problem do this: Sit sideways in the engine compartment when the engine is not running and put your hands on the top of the engine and try to move the engine from side to side. If there is a lot of play then engine mounts might be the problem.

Sometimes if they are weak they'll only show vibration when the engine is in gear.
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Old 13-09-2015, 21:11   #14
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Re: Vibration at > 1400 RPM

I experienced similar vibration at a moderate rpm last season on my C&C and left it go all through summer. Pulled the cutlass bearing this spring and yes it was shot alright and the shaft scored also! Replaced both and runs beautifully now. What would you do underwater if you pulled the shaft and were lucky enough to see if the shaft was still good or not? Better haul out and be safe.
Good luck, whatever way you go!
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Old 14-09-2015, 09:48   #15
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Re: Vibration at > 1400 RPM

Wow, thank you very much for all the answers, you are all very helpful!!

I tried to move the engine as descriped. But there is no movement.

I am now in a harbour which I will leave tomorrow. If we stay in a bay tomorrow for overnight, I will go diving and see in which direction I can move the Prop/Shaft.

I will post the update then.

I am not very good in repairing this things, since I don't have the knowledge and the required tools. If I look the Video of replacing this bearing I will never be able to do that by myself. Maybe I have to hull out then.

Actually I am in Spain and in 2 Months I want to go over the Atlantic. Hopefully with less vibration... but if I am sailing, and put the reverse-gear, then the vibration of course stops.

By the way: I am not sure if it is important or not: But the worst vibrations I get, when I drive forward with about 4 knots and then have to stop immediately (for example in a harbour while maneuvering). So from neutral in Reverse and giving maybe 1400 RPM while the boat still drives forward. Then the vibrations and the noise are really awful...

So, you I will post again tomorrow or after-tomorrow... thanks again!!!
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