[Public-List] Vibration

[Mike Meinhold]

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> 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
>
>
>
>
> > On Jul 4, 2019, at 8:07 AM, Winslow Ayer via Public-List <
> 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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