[Public-List] stern tube question
Michael Connolly
crufone at comcast.net
Fri Feb 1 11:15:02 PST 2019
David,
I didn't mean any disrespect. Just trying to give you some sound advice. In some way I feel connected to all the Albergs out there. Carry on your good work.
Michael
> On February 1, 2019 at 1:49 PM David Fay <davidfay999 at gmail.com> wrote:
>
> Hi Mike,
>
> My comment was really based on my ignorance of how flexible couplings behave: in particular, I was wondering whether they can be flexed out of alignment.
>
> Rigid couplings, in contrast, cannot be flexed out of alignment as far as I know. Instead, the shafts the couplings attach to will bend first or the engine will move on its mounts. As Don Campbell said in one of his comments, it's all about which piece of the drivetrain is the weakest link when the force is applied.
>
> I didn't mean to suggest that alignment issues can be ignored just because I'm using a flexible coupling.
>
> David
>
>
> > > On Feb 1, 2019, at 12:48 PM, Michael Connolly < crufone at comcast.net mailto:crufone at comcast.net > wrote:
> >
> > David,
> > In this situation I would only use a flexible coupling for it's sound deadning effects, not for alignment issues. The coupling needs to be accurately aligned regardless if it is flexible or not.
> > Michael
> >
> > > > > On January 31, 2019 at 9:12 PM David Fay via Public-List < public-list at lists.alberg30.org mailto:public-list at lists.alberg30.org > wrote:
> > >
> > >
> > > Mike,
> > >
> > > But isn't it also possible that the engine/gearbox is aligned with the stern tube but the prop shaft and its flange are not aligned with the gearbox and its flange? What I have in mind is that my flexible coupling, which sits between the prop shaft flange and the gearbox flange, might be damaged (or flexed). In that case, the prop shaft should wobble when I rotate it.
> > >
> > > I don't know if this is even possible, but it occurs to me that a flexible coupling might not behave like a rigid flange bolted to another rigid flange.
> > >
> > > David
> > > Blue Teal #284
> > >
> > > > > > > On Jan 31, 2019, at 4:55 PM, Mike Lehman via Public-List < public-list at lists.alberg30.org mailto:public-list at lists.alberg30.org > wrote:
> > > >
> > > > The cutlass bearing housing dictates the tube alignment. If the shaft is
> > > > not centered in the tube, the the engine is out of alignment. It is highly
> > > > unlikely to bend a shaft that is 7/8" as short as the A30 shaft...there
> > > > isn't enough leverage.
> > > >
> > > > On Thu, Jan 31, 2019, 4:31 PM David Fay via Public-List <
> > > > public-list at lists.alberg30.org mailto:public-list at lists.alberg30.org wrote:
> > > >
> > > > > > > > > Clay,
> > > > >
> > > > > Interesting that you mention shaft alignment because, when I removed my
> > > > > bearing housing, my shaft was not centered in the stern tube. I'm about to
> > > > > tackle that problem. If it is off-center but doesn't wobble, I guess I have
> > > > > an alignment problem. If it does wobble, either the shaft is bent or the
> > > > > shaft is not aligned properly with the gearbox flange.
> > > > >
> > > > > I think the problem began when I had a bad rope wrap around the prop shaft
> > > > > last fall in a squall. It didn't stop the engine but the rope melted from
> > > > > the heat. Since the rope was attached to the bow of the boat (a long
> > > > > unstowed bow line), it could have exerted some sideways force on the prop
> > > > > shaft when the rope tightented. I doubt it would be enough to bend a 7/8"
> > > > > stainless steel shaft, but what do I know.
> > > > >
> > > > > Complicating the whole matter is that I have a flexible coupling between
> > > > > the shaft flange and the gearbox flange. It could be that the flexible
> > > > > coupling was damaged and needs to be replaced. Or perhaps just re-aligned.
> > > > > We'll see.
> > > > >
> > > > > David
> > > > > Blue Teal #284
> > > > >
> > > > > > > > > > > On Jan 30, 2019, at 9:59 PM, Clay Pass via Public-List <
> > > > > >
> > > > > > > > > > > public-list at lists.alberg30.org mailto:public-list at lists.alberg30.org > wrote:
> > > > >
> > > > > > > > > > > I would check to make sure the shaft is coming directly out of the center
> > > > > > of the stern tube and rotate it by hand to make sure it doesn't wobble on
> > > > > > rotation.
> > > > > >
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