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post #1 of 14 Old 05-12-2012 Thread Starter
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stuffing box stern tube different dia's???

Hello all

The stuffing box hose on my boat(a contessa 26) is shot. I have dis-assembled, pressed in a new cutlass bearing and am ready to order a new hose, I have a problem. The stern tube and stuffing box "tube" are different dia's.




The pic above is my stuffing box assembly.
The left side of the assembly resembles the stern tube in that they both have a lip and a tube that is smaller in dia than the lip.

- The stuffing box tube(seen above) is slighter bigger than 1 1/2 inch dia. The lip is 1 5/8 dia.
- The stern tube is 1 5/8 dia and it's lip is slightly smaller than 1 3/4 dia.

So I have a problem. I can buy stuffing box hose 1 3/4 dia which fits the stern tube but will be a loose fit on the stuffing box tube. If I can find hose with an inside dia of 1 5/8's(my local supplier can't) I have trouble getting it onto the stern tube. In theory the hose could be heated and pressed onto the larger stern tube but IMHO this is asking for trouble.

What to do??

Below are just thoughts, please feel free to point out the really bad idea's
1) But a new stuffing box tube that will work for a 1 3/4 dia hose. Any idea where I can get one. It must work with a 7/8's shaft.

2) Build up the dia of the stuffing box tube with some fancy tape to allow a 1 3/4's hose to fit.

3) I have a metal lathe at home and would consider doing the following. Turn off(remove) the lip on the stuffing box tube. Buy some delrin, drill and turn it to fit over the tube to build it up to the correct size. This would include turning in a lip. The delrin would be held in place with two grub screws threaded thru the delrin into the original bronze tube.
This assumes I can find delrin in a size that works for this purpose. Finding bronze tube would be even harder to find I suspect.


For what it is worth I have no reason to believe that this assembly is not original to the boat. My father bought the boat in 1999 from the original owner. Up till 1999 the boat saw light use. Dad never replaced the hose.
I can tell you that I suspected that this would be a problem as I pulled off the old hose. Visually the two ends looked different sizes. How the builder was able to get this to work is beyond me, but it did work(till now)
Unfortunately I had to pretty much destroy the old hose to get it off so I can't take accurate measurements to determine what it's size is.

John

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Last edited by johnnyandjebus; 05-12-2012 at 06:57 PM.
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post #2 of 14 Old 05-12-2012
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Re: stuffing box stern tube different dia's???

Slip a short length of rubber hose over the stuffing box,as a shim to increase its diameter.

Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"
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post #3 of 14 Old 05-12-2012 Thread Starter
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Re: stuffing box stern tube different dia's???

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Originally Posted by Brent Swain View Post
Slip a short length of rubber hose over the stuffing box,as a shim to increase its diameter.
Brent

Thanks for that, it is a good idea. Perhaps I am over thinking this?

John

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post #4 of 14 Old 05-12-2012
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DON'T do it!!

I disagree with Brent - too much hose thickness can result in a "squishy" - technical term - connection between the hose clamps and something solid.

For safety's sake, I would renew the stuffing tube to match your 1-3/4" hull boss. You can buy one here (no affiliation):

PACKING BOX ASSEMBLY BRZ .88" SHAFT 1.75" HOSE 138575

Well worth the $80 or so and cheap insurance.

Even better, consider installing a PSS mechanical shaft seal, and do away with the packing altogether!
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post #5 of 14 Old 05-12-2012
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Re: stuffing box stern tube different dia's???

I agree with Bellatrix. Only $80 and you get a new hose and a new stuffing box.

Last edited by JimsCAL; 05-13-2012 at 07:52 PM.
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post #6 of 14 Old 05-12-2012
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Re: stuffing box stern tube different dia's???

While I agree that a new stuffing box is cheap (~$80) as boat bucks go I do think you are over thinking this a little bit.
That stuffing box hose, that I call a shaft log hose should have 2 hose clamps on either side as it is under the water line. The hose clamps should tighten up to a water tight fit. Get good hose clamps for this.
We had to soak our new piece of hose in boiling water to loosen it up enough to get it onto our stern tube when we replaced it this spring. Suggest you do the same with the 'looser' side when you install it and let the hose clamps do their work.
It seems that Buck Algonquin only carry this hose with ID dims of 1-1/2" or 1-3/4". You will need the 1-3/4" hose no doubt. Hose For Packing Box 1 1/2""I.D. For 3/4"" Shaft

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post #7 of 14 Old 05-13-2012
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Re: stuffing box stern tube different dia's???

Hmmm.... How long was the other hose on there with different diameter shaft log and stuffing boxes? Did it leak before? Perhaps the difference is just not enough to matter as the hose is a but squishable / stretchable.

That was my reasoning when I ran into the same issue recently, I guess we'll know sometime in the next 10 years if I was wrong!

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Re: stuffing box stern tube different dia's???

Thanks for all of the replies including the source for the packing box assembly.
I have ordered the 1 3/4 inch hose and will see how it fits as is. It is more than twice as long as I need so I have extra to work with. The boat is out of the water for the summer so I am in no hurry to get this done.

John

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post #9 of 14 Old 05-13-2012
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Re: DON'T do it!!

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Originally Posted by Chris12345 View Post
Strongly disagree. Do it.

The extra hose needed to adjust to the correct diameter will have about 2.5mm wall thickness. How can that add any harmful amount of squishyness???

Plus, the old assembly obviously lasted a decade or a few, very likely with a hose of one diameter hose just forced on somehow.
OK - I'll see your "strongly disagree" and raise you one!
Normally, a hose-clamped connection is up against something solid -i.e. the hull boss or the stuffing tube. If you introduce another separate layer of hose, you have added an additional hose-to-hose joint that MIGHT slide and come loose.
Perhaps the OP was unaware of this situation and got lucky for years. Now he IS aware that there is something not right. If this is not fixed properly, and the vessel goes down as a result, his insurance company could refuse to pay - based on his knowledge that there was an abnormal fitting in his propeller shaft assembly. This stuff is too important to "fudge" - not for less than a Ben Franklin!
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post #10 of 14 Old 05-15-2012
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Re: stuffing box stern tube different dia's???

John, since you have a lathe, why not build up 3-4mms of a good filled epoxy on the tube, then turn it down to 1-3/4" so the two match? Epoxy is a structural material, after all. Easier than turing Delrin blocks and fussing with all that.

Or, of course, just buying the new one in the right size.
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