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Old 19-12-2011, 22:22   #1
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Modern Stuffing Box Potentially Dangerous

"One difficulty with this type of installation is that the hose clamps may let go and the stuffing box then comes flying forward leaving a great hole in the bottom of the boat. Unless it is shoved back into place immediately, the boat may flood so badly that a crew not aware of the cause of the flooding, and not realizing how easily it may be stopped is likely to abandon ship. ... Another problem is that as time goes by the rubber hose deteriorates, and if it is not watched and replaced as necessary, it may suddenly split. When this happens stopping the leak is most difficult, since one cannot slip a new hose on the shaft and replace the stuffing gland without pulling the shaft. ... Because of these problems, a yacht classified 100A1 at Lloyd's cannot have this type of installation."

Above refers to a stuffing box hose clamped to a flexible rubber hose, i.e. most every boat that hasn't gone to a dripless seal yet. The previous old fashioned stuffing boxes shown are rigidly bolted to the boat.

From: The Ocean Sailing Yacht Volume 2 Donald Street, copyright 1978 pg 456

So how many years until the dripless seals are looked upon as safe and ordinary?

Street does write about the advantages of the new flexible mount stuffing box in the previous paragraphs.


John
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Old 19-12-2011, 22:35   #2
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Re: Modern stuffing box potentially dangerous

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Originally Posted by cal40john View Post
"One difficulty with this type of installation is that the hose clamps may let go and the stuffing box then comes flying forward leaving a great hole in the bottom of the boat. Unless it is shoved back into place immediately, the boat may flood so badly that a crew not aware of the cause of the flooding, and not realizing how easily it may be stopped is likely to abandon ship. ... Another problem is that as time goes by the rubber hose deteriorates, and if it is not watched and replaced as necessary, it may suddenly split. When this happens stopping the leak is most difficult, since one cannot slip a new hose on the shaft and replace the stuffing gland without pulling the shaft. ... Because of these problems, a yacht classified 100A1 at Lloyd's cannot have this type of installation."

Above refers to a stuffing box hose clamped to a flexible rubber hose, i.e. most every boat that hasn't gone to a dripless seal yet. The previous old fashioned stuffing boxes shown are rigidly bolted to the boat.

From: The Ocean Sailing Yacht Volume 2 Donald Street, copyright 1978 pg 456

So how many years until the dripless seals are looked upon as safe and ordinary?

Street does write about the advantages of the new flexible mount stuffing box in the previous paragraphs.


John
Sorry John you lost me right at the start.???
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Old 20-12-2011, 01:38   #3
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Re: Modern stuffing box potentially dangerous

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Sorry John you lost me right at the start.???


In 1978 the then what appears to be a relatively new idea, and what today has become common and ordinary, the stuffing box on a hose seemed to be considered a potential problem for sinking your boat. Street wrote that you could not have one of these on your boat if you wanted an 100A1 Lloyds rating.

Now many people are worried that dripless seals are a potential problem and say that they will stay with the now considered safe stuffing box on a hose.

In 30 years when the next better prop shaft seal comes out people will probably be saying, nope that's dangerous, I'll stick with the dripless seal.

I can see where changing from a big hunk of bronze bolted to the boat to a rubber hose would cause people to question the reliability, but the change from a rubber hose to a rubber bellows doesn't seem to be that big of a stretch (Get it?). The rubber hose and bellows seem to me to have very similar problems for stopping the leak when they fail.

Just thought it was kind of funny. Too subtle maybe. There that fixed it

John
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Old 20-12-2011, 03:21   #4
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Re: Modern stuffing box potentially dangerous

Ok now I get it, I too have a PPS and belive there is very little stress on the bellows due to the friction or lack there of on the graphite to s/s face. I would have thought Lloyds had changed their rating, if not they should.
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Old 20-12-2011, 03:21   #5
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Re: Modern stuffing box potentially dangerous

Profiseal
the only way for a safe stuffing box, although i still have a old hose style one. but actually i do not like so much......
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Old 20-12-2011, 03:37   #6
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Re: Modern stuffing box potentially dangerous

I think you guys are wishing for spring so we can all go back to boating.

The rubber hose connected bronze stuffing box has stood the test of time and is as reliable as anything. Replace the hose and clamps every 10 years or so and pack it with Goretex and you won't have to worry about it for another 10 years.

The dripless seals with their thin corregated boot worries me a lot more than a heavy hose and bronze stuffing box.

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Old 20-12-2011, 07:53   #7
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Re: Modern stuffing box potentially dangerous

That was one of the points. The hose mounted stuffing box has over time proven its reliability. Over 30 years ago it had not. The information about Lloyds is over 30 years old, I assume their policy changed a long time ago. Most likely in 30 years the dripless will be in the same category. Though actually dripless is not exactly new at this point. I didn't know how old my bellows was as it came with the boat. When I called PSS on another matter they asked about the bellows and identified mine as over 12 years old as they had changed the design that long ago.

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Old 20-12-2011, 09:23   #8
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Standard stuffing box. Simple, reliable, inexpensive. Why change?
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Old 20-12-2011, 09:41   #9
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Re: Modern stuffing box potentially dangerous

The point is, each time a new technology appears (new stuffing box, new anchor, new hull shape...), it is considered with skepticism by yachtsmen. They don't hurry to adopt it, because they know it could sink their boats in case of failure.

Then, some yards will propose the new technology and highlight its advantages. Some yachtsmen will purchase it, some defects will appear and possibly be corrected. After some time, it may be more widely accepted, for those situations where it is a real improvement.

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Old 20-12-2011, 09:46   #10
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Re: Modern stuffing box potentially dangerous

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Standard stuffing box. Simple, reliable, inexpensive. Why change?
You are in the same category as the person that 30 years ago said stay with the rigid bolted to the boat stuffing box. To varying degrees we're all in that boat, after all we're on sailboats, we haven't moved on to powerboats.

I was just trying to point out the irony of acceptance over time. See!
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Old 20-12-2011, 09:54   #11
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Re: Modern stuffing box potentially dangerous

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The point is, each time a new technology appears (new stuffing box, new anchor, new hull shape...), it is considered with skepticism by yachtsmen. They don't hurry to adopt it, because they know it could sink their boats in case of failure.

Then, some yards will propose the new technology and highlight its advantages. Some yachtsmen will purchase it, some defects will appear and possibly be corrected. After some time, it may be more widely accepted, for those situations where it is a real improvement.

Alain
Thank you for getting it, in the future I will restrain myself from posting my obtuse humor.

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Old 20-12-2011, 09:54   #12
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Re: Modern stuffing box potentially dangerous

hose clamps may let go? i would be willing to bet that even if the clamps were gone the hose would stay in place with great resistance. have you ever tried to remove a 1.5" hose that has been clamped down for a while?
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Old 20-12-2011, 09:55   #13
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Re: Modern stuffing box potentially dangerous

Interesting. I assume the bellows which may or may not have existed on my boat was changed to a hose because I have a dripless made by Strong and it uses a hose with double hose clamps rather than a bellows. I previously had a stuffing box on a different boat which could leak as well as any hose problem. The leaks however are never that big because the clearance between the log shaft and shaft should be fairly small. A good bilge pump should keep up.
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Old 20-12-2011, 10:05   #14
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Re: Modern stuffing box potentially dangerous

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Interesting. I assume the bellows which may or may not have existed on my boat was changed to a hose because I have a dripless made by Strong and it uses a hose with double hose clamps rather than a bellows. I previously had a stuffing box on a different boat which could leak as well as any hose problem. The leaks however are never that big because the clearance between the log shaft and shaft should be fairly small. A good bilge pump should keep up.
You have a lip seal which is a different kind of dripless.

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Old 20-12-2011, 10:22   #15
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Originally Posted by cal40john

You are in the same category as the person that 30 years ago said stay with the rigid bolted to the boat stuffing box. To varying degrees we're all in that boat, after all we're on sailboats, we haven't moved on to powerboats.

I was just trying to point out the irony of acceptance over time. See!
New technology is great when it offers a real advantage. Say GPS over paper charts or the simplicity of ipad apps as gps backup versus having an extra gps unit. When the advantage is significant then it is easy to sell. In the stuffing vs dripless I dont see that. At least not yet.
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