[Public-List] cutlass housing replacement

[David Fay]

Hi Greg,

A year or two ago, when I replaced my cutless bearing, I noticed that my housing had a cut in the threads just like yours. But I thought it would be fine, so I put my boat back in the water. However, as soon as it hit the water, water started leaking around the outside of the stern tube  and I couldn't stop it, so I had to pull the boat out again. After I disassembled everything, I found that the threads on the end of my stern tube were pretty sketchy also, so I ended up replacing the whole stern tube with a fiberglass one.

I still have my old cutless bearing housing and you're welcome to it if you think you can use it. I could send you pictures but you may decide it's no better than yours.

As far as your plan to use sealant to keep water from bypassing the stern tube -- I'm skeptical. Water under pressure is really hard to keep out. And your stern tube is old and may get worse when you remove it to add sealant. I guess you could try it and see if it works, but I can tell you from experience, if it starts leaking while you're in the water, you're going to be very unhappy.

Instead of taking the risk, I would recommend either: (a) replace the stern tube housing with a new one (I found one online when I was thinking of doing that, but I can't find the link now); (b) replace your stern tube with a longer fiberglass one, in which case you won't need a housing.

Also, here is a description of replacing my stern tube that I wrote up last year. It might be useful to you:
==================================================
Hi Gerard,

It did not occur to me that the threads needed tape or caulk (mine just had grease) but it makes sense. You really don't want water to escape through that joint.

But that wouldn't have solved my problem. My problem was that a big chunk of threads were missing from the end of the stern tube because someone at some time had sawn into them with a hack saw blade while trying to remove a cutless bearing. (A standard way to remove a recalcitrant cutless bearing is to cut it in several places from the inside with a hacksaw blade and then collapse it on itself.) There was enough of a hole in the threads on the end of the stern tube that water was able to escape the tube.

So why hadn't the stern tube been leaking ever since the hacksaw episode? I'm not sure but I think that when I was removing the bearing housing, I rotated the stern tube a bit and that may have sprung the leak.

I bought my fiberglass stern tube from Spartan Marine because I keep my boat at Derecktor Robinhood Marina and Spartan is right there. They also had a cutless bearing that fit the tube they had and installed it for me (did a nice job too). I don't remember the exact length of the tube but it was around 11 inches. You should measure your boat for the length and diameter of the tube you need. Its length will depend first on how far it sticks out behind the hull, which depends on how much room you have in front of your prop and how much room you want to leave for prop shaft zincs. It will also depend on how far it penetrates inside the boat, which in turn depends on where it needs to attach to your stuffing box hose.

The outside diameter of the stern tube will be determined by the hole in your hull that the bearing housing occupied -- in other words, the stern tube outside diameter will be the same as the outside diameter of the forward end of the bearing housing, the part that the stern tube screws in to (wish I had a picture). The inside diameter of the stern tube will be determined by the diameter of your prop shaft (usually 7/8") and how much clearance you need around it (the inside diameter of your old stern tube would be about right).

In all of this, I am assuming that you will replace both the stern tube and the bearing housing with a single fiberglass stern tube, like I did. There may be a way to replace just the stern tube with a fiberglass one and retain the bearing housing, but I don't know how you would mate the two.

In any event, it's not necesssary to get a fiberglass stern tube from Spartan Marine -- in fact, I'm not even sure they offer them in their catalogue. But there are plenty of other companies out there that do sell them. This may be helpful also: a step-by-step description of a stern tube replacement on a Pearson Triton by Tim Lackey with lots of good pictures: https://www.lackeysailing.com/archived/daysailor/rebuilding/systems/sterntube.htm <https://www.lackeysailing.com/archived/daysailor/rebuilding/systems/sterntube.htm>

About glassing in the stern tube: that's exactly what I did (and what Tim Lackey did), even though some people warn against it (because it's too permanent, I suppose). If you do that, just make extra sure that you properly align the stern tube with the engine because it's going to be really hard to change the alignment of the stern tube if you get it wrong.
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David

> On Jan 17, 2021, at 1:00 PM, Greg Wallis via Public-List <public-list at lists.alberg30.org> wrote:
> 
> Hi,
> 
> I am in process of replacing the cutlass bearing,
> 
> Here's a link to my poor cutlass bearing housing.  Notice the ruined pipe
> threads.
> https://drive.google.com/file/d/198AJ_rMD7Lx8QrdksGXhIbeRR6_FPS9t/view
> 
> I took the cutlass bearing housing to a shop to have the new bearing
> pressed in, and they proceeded to overcut the old bearing and cut two deep
> groves lengthwise through the female pipe threads of the cutlass housing.
> These threads connect the cutlass bearing housing to the stern tube.  So
> now the threads are not going to be watertight.  I think that the threads
> will still function, but they will most certainly leak.
> 
> I am hoping somebody has an identical alberg30 cutlass bearing housing that
> they'd be willing to sell to me.  This would be the best.
> 
> If I can't find another one, I am considering to allow this fitting to leak
> between the stern tube and the cutlass bearing housing.  I think I'd just
> need to ensure that there is plenty of sealant around the outside of stern
> tube where it exits the hull.  I guess some water would accumulate in that
> space and wouldn't really have anywhere to go.
> 
> I would also put a generous layer of sealant on the threads themselves, to
> hopefully prevent it from leaking at all.   Doing this is going to make it
> very difficult to remove the cutlass bearing housing in the future.
> 
> If you have any suggestions or tricks to make these threads watertight
> again, please do let me know.  How about a thread sealant that would solve
> this problem and still be possible to unscrew in the future?
> 
> Ideally though, if you have a cutlass bearing housing you'd be willing to
> part with, please let me know!
> 
> Thanks
> Greg
> hull #165
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