[Public-List] Vibration

[Gordon Laco]

Back in my wooden boat days, TOUCH WOOD’s winches would ring and vibrate at certain speeds under power.  I fell into the habit of putting a bit of masking tape on the upper ring plates to silence them…. 

Ah, loved that boat.   It was one of her quirks.

Gordon Laco
www.gordonlaco.com




> On Jul 4, 2019, at 9:08 AM, Mike Meinhold <meinhold272 at gmail.com> wrote:
> 
> Many things on your boat have natural frequencies that will match one of the harmonics of your engine rpm and blade frequency .  When I had an Atomic 4 and Southcoast winches, they would ring at about 1800 rpm. 
> 
> On Thu, Jul 4, 2019 at 08:13 Gordon Laco via Public-List <public-list at lists.alberg30.org <mailto:public-list at lists.alberg30.org>> wrote:
> Good morning - 
> 
> It could be alignment… it could also be cutless bearing wear.   The prop shaft goes through two bearings on it’s way out the stern.   
> 
> One, called ’the gland’ in the old days, is the semi-watertight seal that keeps the water out.  The other, the cutless bearing, holds the shaft in place.  It is the outer one and the one you can see just ahead of the prop when the boat is out of the water.   This bearing is made of hard rubber and is designed to be water lubricated… not a waterproof seal at all.
> 
> It eventually wears.   At lower rpm speeds your may still be doing it’s job… at higher speeds minute eccentricity in either the balance or alignment of your shaft and prop may be taking advantage of the wear and letting the shaft begin ‘chattering’ at those higher speeds.
> 
> 
> Gordon Laco
> 426 Surprise
> www.gordonlaco.com <http://www.gordonlaco.com/>
> 
> 
> 
> 
> > On Jul 4, 2019, at 8:07 AM, Winslow Ayer via Public-List <public-list at lists.alberg30.org <mailto:public-list at lists.alberg30.org>> wrote:
> > 
> > Does anyone have thoughts on why I get a vibration above 1200-1300 rpm’s when motoring? I have a feeling that it may be in the alignment of the shaft but I don’t know.
> > It’s not unbearable but it is annoying (and loud).
> > 
> > Thanks for any advice,
> > 
> > Winslow Ayer 
> > Tinkers Damn #283
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