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beast

Vibration. Sloppy rudder

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beast

93 Sunsetter. Bought the boat last summer, prop had a small ding on one of the blades but had very, very minimal vibration. At the end of the summer, idling into a cove hit a rock with the prop. Had a good amount of vibration after that & limped it across the lake. Stored the boat for the winter, had prop repaired. First trip out this summer (with repaired prop) & had alot of vibration. Pretty much through the whole RPM range & in reverse. Not as bad when cruising. I know first thing I should have done was try another prop. Well I don't have one, & the place that repaired it assured me it was balanced. Found a little play in the strut (cutlass) bushings...not much. So I check the alignment, & it's perfect. Check the shaft, not bent. In the process of pulling the shaft I noticed a good amount of slop in the rudder, in all directions. Pulled the rudder, red bushings look fine, a little grooving in the rudder, not much. O-rings are in place, but smashed down. (this is a greaseless rudder, no zerk) Replaced strut bushings. Put the boat in the water, & still have the same vibration. So after this long winded post, my question is.....will this sloppy rudder cause the vibration? Is there supposed to be a little play in the rudder box? I also noticed on high speed sharp turns that the boat really howls, coming from the rear of the boat. I put my hand on the prop shaft stuffing box while under way & don't feel any vibration there. Also put my hand on the rudder arm while underway & it's not flopping around, but I do feel some vibration. I know, I know try a different prop, right? HELP!!

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99response

The rudder most likely had that play last summer when you hit bottom.

Stainless prop or Nibral?

Also you checked the shaft but what about the strut?

-Chris

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BillFooter

If a sloppy rudder was the problem I think you would have had the vibration before you dinged the prop. My bet is the prop. I would check to make sure it is properly seated on the shaft. If it is seated correctly then the prop repair would be suspect. Could you have damaged the rudder when you dinged the prop?

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beast

Nibral prop. Strut is not bent. Prop is seated correctly. No marks or damage to the rudder that would lead me to believe it was hit. I barely hit the prop. The rudder appears to be straight. I thought that the the rudder had to have had the play in it last summer, but I didn't notice it until the other day when I had to pull it to get the shaft out. I'm leaning towards the prop also. I should have tried another one first & saved myself 3 hours in the 95+ heat replacing strut bushings that were probably fine.

Next question is how much play should there be in the rudder assembly? Is it even possible to get such vibration with a loose rudder? Like I said the bushings looked good, but the rudder has alot of slop. Would replacing the O-rings in the bushings solve that problem?

Edited by beast

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99response

How much is *alot*

I would try another prop honestly, espeically with a fresh rebuild.

-Chris

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SFD

I vote on the prop. I had two reworked, they were older styles, good reworks but still vibrated a little when you felt the pylon, nothing to worry about. I have a new Acme on now and it does not vibrate at all -

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beast

SFD...thats exactly where I feel/hear it the most, in the pylon...DRIVES ME CRAZY! It's not a violent vibration, more like reverbs through the hull. I'm gettin' a new prop! So is the guy who reworked it just a hack? Cost me $110. I guess I'll send it back.

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tvano

one of the prop rebuilds i had done a few decades back was returned to me 'balanced'.

dropped it on the shaft and spun it slowly.

one of the lobes was an inch longer than the others.

didn't even have clearance to swing.

thank my lucky stars i caught it before i dropped it in the lake.

Edited by tvano

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beast

UPDATE: It was the prop. Put on a new Acme 541. No vibration whatsoever, sloppy rudder & all. Needless to say I'll be taking the other prop back to be rebalanced Mad.gif

Edited by beast

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