[Public-List] Public-List Digest, Vol 4012, Issue 1
Kris Coward
kris at melon.org
Thu May 28 13:58:17 PDT 2020
Your assumption that the same bolt holes will produce the same alignment
isn't one that's ok to make over the distances being considered. There's
always a bit of clearance or slop in unthreaded bolt holes, so between
that, and the lack of any ability to guarantee consistent thickness of
sealant between the housing and the hull, the alignment can change
(enough to be outside the tolerances for the motor and coupling).
-K
On Thu, May 28, 2020 at 03:26:26PM -0500, Marcelo D. Gentinetta via Public-List wrote:
> I have been following this issue with the leaking stern tube for future reference. I am curious as to why the shaft needs to be re-aligned after changing the stern tube. My thinking process is that if you screw the cutlass bearing housing onto the new bronze stern tube and then re-bolt the housing into the original holes the shaft should exit the hull at exactly the same place it was before therefore the alignment should stay the same. Am I missing something?
> Thanks,
> Marcelo
> #441
>
> > On May 28, 2020, at 2:19 PM, Daniel Swords via Public-List <public-list at lists.alberg30.org> wrote:
> >
> > I had a very similar experience. The caulking is not for sealing the stern tube, it is just structural support. I originally thought that was the source of my leak but it wasn’t. The stern tube is threaded into the cutlass bearing housing on the outside of the keel and that should be a water tight seal so water is sealed inside the stern tube by the screwed connection on one end and the stuffing box or dripless seal on the other. I have some excellent photos. Anyway, my stern tube leaked because the threaded section had developed a crack allowing water to get outside of the stern tube and into the boat. The fix was to haul the boat, remove the cutlass bearing housing from the outside (easy to do), replace the stern tube with a new threaded bronze pipe, and reattach the cutlass bearing housing. The first boat yard I went to quoted removing the engine and fixing the leak then reinstalling the engine. That would certainly work and the job would be easier, but expensive. The second boat yard left the engine in place but did realign the shaft after replacing the stern tube. Much cheaper. If I were to do this again I would cut out and remove the entire cockpit floor for better access. Then I would reinstall the cockpit floor in a fashion that would allow future removal. I do not believe this job can be done in the water (my opinion).
> >
> >
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> >
> >
> > On Thursday, May 28, 2020, 1:31 PM, public-list-request at lists.alberg30.org wrote:
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> > ======================================================
> >
> >
> >
> > Today's Topics:
> >
> > 1. Stern tube (Gerard Kuperus)
> > 2. Re: Stern tube (David Fay)
> > 3. Re: Stern tube (Gerard Kuperus)
> > 4. Re: Stern tube (George Dinwiddie)
> > 5. Re: Stern tube (David Fay)
> >
> >
> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Thu, 28 May 2020 05:26:56 +0000
> > From: Gerard Kuperus <gkuperus at hotmail.com>
> > To: "public-list at lists.alberg30.org" <public-list at lists.alberg30.org>
> > Subject: [Public-List] Stern tube
> > Message-ID:
> > <BYAPR14MB2775282EE782BAF4A14466FCD78E0 at BYAPR14MB2775.namprd14.prod.outlook.com>
> >
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > Hello Alberg 30 folks,
> >
> > In the fall I hauled Skye Mist, redid the bottom and with the aid of the helpful guides on the Alberg 30 site I managed to successfully replace the cutless bearing. When I was back in the water I noticed some leaking. I assumed it was the rudder post. I forgot about it and the leak seemed to have disappeared. The last couple of weeks it has returned and I finally figured out the stern tube is leaking where it is connected to the hull. It is sealed with a dark grey rubbery caulk spread out liberally at the top, less so at the bottom, which is hard to reach. A couple of questions: what is this caulking? How should I fix the leak (in the water)? Any suggestions for getting better access to this area?
> > Thank you!
> > Gerard
> >
> >
> > ------------------------------
> >
> > Message: 2
> > Date: Thu, 28 May 2020 06:14:17 -0400
> > From: David Fay <davidfay999 at gmail.com>
> > To: Alberg 30 Public List -- open to all
> > <public-list at lists.alberg30.org>
> > Cc: Gerard Kuperus <gkuperus at hotmail.com>
> > Subject: Re: [Public-List] Stern tube
> > Message-ID: <C3C1C4C2-99F2-4EE7-B70B-76EBEE7D62BB at gmail.com>
> > Content-Type: text/plain; charset=us-ascii
> >
> > Hi Gerard,
> >
> > The "dark grey rubbery caulk" is called thiokol, https://polyspec.com/products/thiokol/thiokol-2235m/ <https://polyspec.com/products/thiokol/thiokol-2235m/>. It's also known as Satan's caulking, if you try to remove it (http://svcookie.blogspot.com/2011/10/thiokol-satans-caulking.html <http://svcookie.blogspot.com/2011/10/thiokol-satans-caulking.html>).
> >
> > You need to determine where the water is coming from. One possibility is that it has found its way between the outside of the stern tube and the thiokol. This is a serious problem that may require replacement of the stern tube.
> >
> > The other possibility is that your hose, which runs between the bronze stuffing box and the forward end of the stern tube, is not attached tightly enough to the stern tube. So the water is coming through the stern tube, which it should, but then leaking out the joint between the hose and the stern tube, which it shouldn't. In this case, all you have to do is tighten the hose clamps sufficiently to stop the leak.
> >
> > I had a similar leak on my boat and ended up having to replace the stern tube. I can provide some guidance on how to do that.
> >
> > David
> > Blue Teal, #284
> >
> >
> >
> >> On May 28, 2020, at 1:26 AM, Gerard Kuperus via Public-List <public-list at lists.alberg30.org> wrote:
> >>
> >> Hello Alberg 30 folks,
> >>
> >> In the fall I hauled Skye Mist, redid the bottom and with the aid of the helpful guides on the Alberg 30 site I managed to successfully replace the cutless bearing. When I was back in the water I noticed some leaking. I assumed it was the rudder post. I forgot about it and the leak seemed to have disappeared. The last couple of weeks it has returned and I finally figured out the stern tube is leaking where it is connected to the hull. It is sealed with a dark grey rubbery caulk spread out liberally at the top, less so at the bottom, which is hard to reach. A couple of questions: what is this caulking? How should I fix the leak (in the water)? Any suggestions for getting better access to this area?
> >> Thank you!
> >> Gerard
> >> _______________________________________________
> >> These businesses support your Association:
> >> http://www.alberg30.org/store/A30supporters.html
> >> Please support them.
> >> _______________________________________________
> >> Public-List mailing list
> >> Public-List at lists.alberg30.org
> >> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
> >
> >
> >
> > ------------------------------
> >
> > Message: 3
> > Date: Thu, 28 May 2020 15:32:48 +0000
> > From: Gerard Kuperus <gkuperus at hotmail.com>
> > To: David Fay <davidfay999 at gmail.com>, Alberg 30 Public List -- open
> > to all <public-list at lists.alberg30.org>
> > Subject: Re: [Public-List] Stern tube
> > Message-ID:
> > <BYAPR14MB2775DCEE01ABC6653D8C32A8D78E0 at BYAPR14MB2775.namprd14.prod.outlook.com>
> >
> > Content-Type: text/plain; charset="iso-8859-1"
> >
> > David,
> >
> > That is very helpful, although not necessarily good news: it is indeed leaking from the Thiokol. Since I do not plan another haulout right now, what would be my best options to stop the leak for now. Could I use a sealant on it that can be applied to wet surfaces? Some underwater epoxy?
> > As far as I could tell when I replaced the cutlass bearing is that the stern tube is in good shape. I think that because of the movement with removing the bearing a weak point in the Thiokol (at the bottom there is only a thin section, less than a 1/2 inch, at the spot where I saw water, probably a 1/4 of an inch) gave up. Maybe that is wishful thinking, but I hope I can simply fix it, at least for now with an adhesive that works in wet conditions and sticks to fiberglass and Thiokol. I can then again assess at the next haul out.
> >
> > Suggestions?
> >
> > Gerard
> >
> >
> >
> > ------------------------------
> >
> > Message: 4
> > Date: Thu, 28 May 2020 11:36:43 -0400
> > From: George Dinwiddie <gdinwiddie at alberg30.org>
> > To: public-list at lists.alberg30.org
> > Subject: Re: [Public-List] Stern tube
> > Message-ID: <57d2c395-3536-fad2-094d-cad55614cc8d at alberg30.org>
> > Content-Type: text/plain; charset=utf-8; format=flowed
> >
> > Gerard,
> >
> > On 5/28/20 1:26 AM, Gerard Kuperus via Public-List wrote:
> >> Hello Alberg 30 folks,
> >>
> >> In the fall I hauled Skye Mist, redid the bottom and with the aid of the helpful guides on the Alberg 30 site I managed to successfully replace the cutless bearing. When I was back in the water I noticed some leaking. I assumed it was the rudder post. I forgot about it and the leak seemed to have disappeared. The last couple of weeks it has returned and I finally figured out the stern tube is leaking where it is connected to the hull. It is sealed with a dark grey rubbery caulk spread out liberally at the top, less so at the bottom, which is hard to reach. A couple of questions: what is this caulking? How should I fix the leak (in the water)? Any suggestions for getting better access to this area?
> >
> > The caulking around the stern tube holds it in place, but is not
> > required for keeping water out of the boat. Principally that falls on
> > the caulking under the cutless bearing housing. Don't forget to caulk
> > the bolts holding that housing, too.
> >
> > If that's not it, there could be leakage paths at either end of the
> > stern tube. As David says, the hose on the forward end is most likely.
> > Theoretically there's a possiblility for water to leak past the threads
> > at the aft end, but I've never heard of that happening.
> >
> > - George [who has more experience in this area than I want]
> >
> > --
> > ----------------------------------------------------------------------
> > When I remember bygone days George Dinwiddie
> > I think how evening follows morn; gdinwiddie at alberg30.org
> > So many I loved were not yet dead, http://www.Alberg30.org
> > So many I love were not yet born. also see:
> > 'The Middle' by Ogden Nash http://idiacomputing.com
> > ----------------------------------------------------------------------
> >
> >
> >
> >
> >
> > ------------------------------
> >
> > Message: 5
> > Date: Thu, 28 May 2020 14:30:59 -0400
> > From: David Fay <davidfay999 at gmail.com>
> > To: Gerard Kuperus <gkuperus at hotmail.com>
> > Cc: Alberg 30 Public List -- open to all
> > <public-list at lists.alberg30.org>
> > Subject: Re: [Public-List] Stern tube
> > Message-ID: <771D3FA2-5D51-4831-BFC7-B251741AD408 at gmail.com>
> > Content-Type: text/plain; charset=us-ascii
> >
> > Hi Gerard,
> >
> > First, you should know that normally water shouldn't be able to get between the outside of the stern tube and the thiokol packed around it. The water should be prevented from going there by the seal between the cutless bearing housing flange and the hull. (In my case, that seal was good, but the threaded joint between the cutless bearing housing had failed so water was able to get from the inside of the stern tube -- which always has water in it -- to the outside of the stern tube.) Assuming you don't have a problem like mine, it's likely that the sealant between the cutless bearing housing and the hull on your boat has failed. This allows water to seep through the joint and then travel along the outside of the stern tube and into the boat. This is a relatively easy fix but it does require you to haul the boat. You need to: (1) unscrew the two bolts that hold the cutless bearing housing on; (2) unscrew the housing from the stern tube (be sure to keep the stern tube from rotating whi
> > le you're unscrewing the housing); (3) clean up the surface of the housing flanges and the hull; (4) apply a waterproof sealant/adhesive to the flanges (for example, 3M 4200, but some people prefer 3M 5200 or Sikaflex); (5) put everything together.
> >
> > This is the most likely failure path, but there are others. For example, your stern tube itself may have failed, allowing water to get from the inside of the tube to the outside. In this case, you'll have to replace the stern tube, which is what I ended up doing on my boat. That's a much bigger job because it involves taking apart the drive train, putting in a new stern tube and cutless bearing, and then re-aligning the prop shaft and engine when you're done. Let's hope you just have to put some sealant on the housing.
> >
> > David
> >
> >> On May 28, 2020, at 11:32 AM, Gerard Kuperus <gkuperus at hotmail.com> wrote:
> >>
> >> David,
> >>
> >> That is very helpful, although not necessarily good news: it is indeed leaking from the Thiokol. Since I do not plan another haulout right now, what would be my best options to stop the leak for now. Could I use a sealant on it that can be applied to wet surfaces? Some underwater epoxy?
> >> As far as I could tell when I replaced the cutlass bearing is that the stern tube is in good shape. I think that because of the movement with removing the bearing a weak point in the Thiokol (at the bottom there is only a thin section, less than a 1/2 inch, at the spot where I saw water, probably a 1/4 of an inch) gave up. Maybe that is wishful thinking, but I hope I can simply fix it, at least for now with an adhesive that works in wet conditions and sticks to fiberglass and Thiokol. I can then again assess at the next haul out.
> >>
> >> Suggestions?
> >>
> >> Gerard
> >
> >
> >
> > ------------------------------
> >
> > Subject: Digest Footer
> >
> > _______________________________________________
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> > ------------------------------
> >
> > End of Public-List Digest, Vol 4012, Issue 1
> > ********************************************
> >
> >
> >
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--
Kris Coward http://unripe.melon.org/
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