stuffing box replacment

[motion30]

I have an old marine trader 34'* I would like to replace the stuffing box with a pss seal system* This boat has a stern tube with the stuffing box threaded on the end and bolted to a crossmember,*and not much propshaft exposed* Is it possible to refit to a dripless system?

 

[RT Firefly]

Hiya Motion,
***I would suggest, unless the old stuffing box system is damaged, to keep it.* Failure of the bellows on a PSS system could very well sink your boat.*

 

[RickB]

RT Firefly wrote:

I would suggest, unless the old stuffing box system is damaged, to keep it.* Failure of the bellows on a PSS system could very well sink your boat.

I'll second that. I have installed a couple of them but really never have been able to feel all cozy about the things. They just aren't as "bulletproof" as I believe a seal should be and there is no second chance.

Larger versions of mechanical shaft seals usually incorporate an inflatable bladder to seal the shaft when the seal is damaged or fails.

 

[FF]

The PSS setup is far to dangerous and has been replaced with more modern stuffing material.

Duramax and its competition are far superior , function with Zero effort (or danger) with no dripping into the boat.

And no mandatory shaft removal every few years to replace bellows.

 

[sunchaser]

I agree that retrofitting an older standard packing stern tube to PSS is questionable. But using the word "dangerous," as FF has done, to describe PSS systems is a stretch. A stern tube and shaft setup*is like any thru hull - it must be designed right and inspected regularly. Many do not like active stabilizers because they are a big thru hull etc etc. And is your exhaust system designed to live through a rat or muskrat brunch etc etc. And can each and every one of your thru hulls take a 250# load for 30 minutes etc etc*

But this is 2010. There are fly by wire jumbo jets, glass panels and GPS units in aircarft -*that many yet*decry. And even more shocking, the most successful blue water boat manufacturer, Nordhavn, uses PSS systems. Their big *75 and 82 footers use PSS on the 3-1/2 to 4" shafts and nary has one yet sunk due to this "dangerous" situation. Let alone the smaller Nordhavn vessels running around the world that have PSS systems. My PSS dripless systems are working fine and get inspected for temp and leaks every hour I'm cruising. I'd guess far moreso than any standard system gets checked in*most vessels.

So FF and rickB, even though you are both in agreement on this one, the boating world has passed*you by.

-- Edited by sunchaser on Friday 15th of January 2010 08:16:27 AM

 

[RickB]

sunchaser wrote:

the boating world has passed*you by.

*

Hardly.

I work with the latest and best world class yachts where money is*barely an issue when it comes to the machinery installation.*None of these boats use a seal that cannot be closed off, either by an inflateable bladder or by clamping down on some other type of emergency seal.

Show me another*item below the waterline on a boat where the only thing between the sea and thee is a very thin and very flexible rubber bellows with no way to stop flooding when it fails.

"My PSS dripless systems are working fine and get inspected for temp and leaks every hour I'm cruising. I'd guess far moreso than any standard system gets checked in*most vessels."

That's because other systems can be trusted to behave themselves and don't require that much labor.


-- Edited by RickB on Friday 15th of January 2010 09:25:10 AM

 

[sunchaser]

Point made RickB. Note I did not say you are wrong. However, with 1000s of dripless systems out there and more coming, the trend is obvious and well established. And with the mother hens of AYBC continuing to issue guidelines, dripless get a passing mark. It has been some time, but I well recall the article Steve D wrote on packing systems that this Forum's small boat members use. Passive systems hardly get a free pass.

To me "dangerous" is "thin rubber" connected to*100,000s of stern drive bellows, numerous IPS drives, thru hulls for heads, macerators, cooling water*intake, ACs,*washdowns, stabilizers*etc. that hardly ever get inspected until they start*leaking. Just the thought of all these "dangerous" hoses*is enough to make one paranoid --------------

-- Edited by sunchaser on Friday 15th of January 2010 11:02:21 AM

 

[Marin]

sunchaser wrote:

Just the thought of all these "dangerous" hoses*is enough to make one paranoid --------------

On a properly built boat all those "dangerous hoses" are connected to seacocks that can be closed if there is a problem with the hose. On our boat we leave all the seacocks except the two engine raw water seacocks closed unless we are actually using the boat.* Dripless shaft seals are fine (although I don't understand why so many people are so deathly terrified of a bit of water in the bilge) but like any higher-tech system, they require more care and more attention.*

In the eleven years we've owned our boat the flax-packed shaft logs have required adjustment only a couple of times and have only had to be re-packed once and that was only because we had the shafts out of the boat so we figured might as well do it.* They don't drip when the shafts are not turning and they barely drip when they are.* They run dead cold.* I glance at them when I do an engine room check, which is only once per day's run.

Having to climb down into the engine room religiously every hour is not the way I want to go boating.* If the equipment in there is so unreliable or prone to problems that it requires that kind of surveillance, it's not the kind of equipment I would want to have.

*

 

[sunchaser]

Marin* - Have you ever owned a stern drive?* There are no shut off valves on the 3 bellows that each have. Again, there are 100,000s of these out there. And on the new GB IPS systems, where is the shut off valve?* If you are not on your boat to close the thru hull when*the macerator line ruptures, the boat sinks.* I picked on the macerator because it is a PD pump and quite capable of blowing out a sh---y old line.

My dock mates Krogen sank at the dock 6 years ago with closed through hulls. Bonding system went awry. Quite simply there are untold ways for your boat to go down. The most common (non hurricane)according to the insurers - drain plugs and hoses connected to the water system under pressure while the owner is on the boat (or out to dinner)***

It is near impossible to buy a newer boat that does not have a dripless system. I will give you a $100*for every owner who has taken out dripless if you give me $50 for every owner who has installed dripless.

So what we really have here is old boats vs new boats. The train left the station 50 years ago on bellows below the water line. They only have gotten better.


-- Edited by sunchaser on Friday 15th of January 2010 01:21:57 PM

 

[Marin]

sunchaser wrote:
Marin* - Have you ever owned a stern drive?

No, but I have met five people that I can remember who had stern drives and had the boat sink, or start to sink, because of a failed gasket or boot.

I'm sure the technology has come a long way.* But just because dripless systems are becoming the norm on newer boats does not automatically mean that standard packed glands are bad.* They're fine, and from your description they take a hell of a lot less oversight than the dripless system.* A system that requires me to crawl down into the engine room every hour to make sure it's okay doesn't sound like much of an advancement to me, no matter how snazzy the technology is.

I'll take our ancient, low-tech, never-worry-about them flax-packed glands any day over some fancy system that is so potentially trouble-prone I have to keep checking on it whenever I'm running the boat.* That's a step backward in my book.

*

 

[sunchaser]

Marin:

I have owned stern drives for the past 40 years. Not a sinker in the group. Of course I do a little bellows replacement now and then. The Volvo*boot? That went out in the 70s.

I take sandwiches into my ER and wait for my wife to buzz me back to the helm. She can't understand why I spend all that time watching PSS bellows for leaks. I tell her it is a "dangerous" situation and I'm trying to prevent Armageddon. I told her I want Gore and she says "So why did you vote for BUSH?"

Anyway, I'm in Santiago and bored tonight so thought I'd have some fun. Off to Lima in the AM

Lo siento y adios.

 

[Marin]

sunchaser wrote:

I take sandwiches into my ER and wait for my wife to buzz me back to the helm. She can't understand why I spend all that time watching PSS bellows for leaks.

Sounds like a great excuse to get more goodies for the boat.* What you need is a pair (I assume you have a twin) of high-definition color video cameras mounted so they look at the PSS seals with the appropriate lighting.* Then you need a*big 1080p**LCD HD screen*display the camera shots*in a split screen.** Don't get a plasma screen because they are not as sharp as an LCD screen.**And you have to have HD because that's the only way to get sufficient detail to see the splits in the seals developing.*

Then, with the LCD screen mounted where it can be seen from the helm, you and your wife can monitor the health of the shaft seals on a full-time basis from the comfort of a nice seat.* They say two pairs of eyes are better than one.

-- Edited by Marin on Friday 15th of January 2010 07:40:44 PM

 

[RickB]

sunchaser wrote:

Point made RickB. Note I did not say you are wrong. However, with 1000s of dripless systems out there and more coming, the trend is obvious and well established.*

And I never called them "dangerous" but I don't think they are worth retrofitting either. As far as Nordhavn using them, they are cheaper than the better made units and they are probably familiar to the demographic that buys Nordhavns because they advertise in all the magazines.

The seals we use on larger yachts are similar, they use a mechanical seal, hardened metal on ceramic elements, but the rubber* bellows is short and thick and there is an inflatable bladder internally that will seal the shaft if the seal or bellows fails. These are heavy duty, reliable, and provide the degree of protection that the owners of those boats demand.

Just like a valve on a hull penetration, and two hose clamps, having a second layer of isolation is only good practice. To remove a nearly bullet[proof system* just to follow the current fashion is silly in my book. How do you justify the cost and increase in labor, much less give up the reliability of a packed seal?

If I woke up one morning desperate to get rid of a stuffing box on a small boat I would consider the Manecraft "deep sea seal" type as it is much sturdier and incorporates a safety seal to prevent uncontrolled flooding. It is what the ones advertising in PMM pretend to be.

And as far as I/O bellows go ... there is no shortage of flooding/sinking stories related to them. I have seen two and I don't even hang out around the things.

*

*


-- Edited by RickB on Friday 15th of January 2010 08:07:15 PM

-- Edited by RickB on Friday 15th of January 2010 08:07:58 PM

 

[Marin]

Had an interesting conversation about three years ago*with a design engineer at a local marine fabricator that makes radar towers (my reason for being there), driveline components, and sells and distributes other driveline components like dripless shaft seals (PSS).

I asked him what the advantages were of dripless shaft seals. He asked me if we had them on our boat. I said, no. He asked me if we were considering changing over to a dripless system. I said I didn't really know anything about them so didn't know what advantage it offered. His next comment was an interesting take on today's boat buyers (by which I assumed he meant new-boat buyers).

He said to not bother spending money on dripless seals. He said the only advantage they offer over a conventional packing gland is that they don't drip. He said the reason their company carried PSS seals and sold a lot of them was that today's boat buyers generally don't have a clue about the systems on a boat and are not interested anyway. So if they see something dripping or some water in the bilge, they panic and think they're sinking. The dripless seals, he said, were simply a gimmick to provide peace of mind.* This from a guy who sells them.......


-- Edited by Marin on Friday 15th of January 2010 10:40:57 PM

 

[sunchaser]

Hah, now Im in Lima hoping I can get the NFL playoffs. Marin, my ER is walk in and it is great fun to IR gun the 6-8 temp spots per engine*and check things out. Plus Im a gear head. So all the remote sensors in the world could not keep me out during cruising. That is why I buy boats rather than race horses

Two* questions

Marin:
If you won the lotto and bought a new(er) GB or Aleutian, virtually all of which have dripless, what would be your go forward actions regarding the dripless units you purchased.

rickB:
What is the minimum shaft size that could accomodate a safety bladder arrangement and are they used on the smaller shafts that you know of.

 

[Marin]

sunchaser wrote:

If you won the lotto and bought a new(er) GB or Aleutian, virtually all of which have dripless, what would be your go forward actions regarding the dripless units you purchased.

Good question.* I certainly wouldn't replace them unless I was told that dripless seals are really trouble-prone and a failure waiting to happen, in which case I might think about replacing them with standard packing.* But I've not heard that they are and I doubt that GB, Nordhavn, etc. would use them if they were.* So I would simply check them routinely along with everything else in the engine room.* Right now on our boat, that is once during a day's cruise, usually an hour or so after departure when everything is up to temperature.* I also check the engine room before we start up and after we shut down.

However..... if I learned that dripless seals really do require checking every hour--- which is what you say you do--- I would definitely change them for something else because no way in hell am I interested in* crawling around in, or walking around in, a stupid engine room every hour.* The fact that you do this says to me that you have some inherent mistrust of the seals, which in turn tells me maybe they're not all that reliable as they're made out to be.* So if an hourly check is the kind of scrutiny they require to maintain confidence in them, at that point this becomes cause in my mind to get rid of them.* I love operating engines---- I've said before I wish our boat had three of them instead of just two--- but I have absolutely no interest in hanging around watching them or any other system on the boat.* There are more interesting things--- at least when boating in this area-- to watch.

But if dripless seals are truly reliable, or as reliable as anything can be on a boat, it wouldn't bother me at all if our boat boat had them.

Standard packing glands have a track record of a couple of centuries of reliable, no-worry service.* I'm not a big fan of using technology simply for technology's sake, which is one reason I work for Boeing and not Airbus. My point is not that dripless seals are dangerous so they should be changed if a boat has them, but that if a boat doesn't have them there is no bang for the buck in installing them.

 

[RickB]

sunchaser wrote:

What is the minimum shaft size that could accomodate a safety bladder arrangement and are they used on the smaller shafts that you know of.

*

Am not sure but have seen them on under 4" diameter (550 hp vp on a sailboat). The Manecraft seals I mentioned earlier fit shafts down to about an inch. They don't use an inflatable bladder but have a built in section that rides close to the shaft and can be compressed around it with a hose clamp sort of attachment.

If I were to order a newbuild that came stock with dripless seals of the type we have been discussing rather than a stuffing box, I would specify a change to either a stuffing box, the Manecraft style, or if it was a larger boat, the type with an inflatable bladder.

There simply is no justification for installing any device with moving parts that, when it fails, will lead to rapid and uncontrolled flooding and loss of propulsion.

 

[Delfin]

You need about 12 inches of shaft to work with for a PSS system, less with a TIDES.* The reason for dripless shaft seals is because they are, well, dripless.* If that matters to you and you can easily see the shaft seal then I wouldn't worry that much about the technology.* The rubber used on the PSS bellows is quite thick, and as long as you inspect it every once in a while for cracks, I'm not sure what the panic is.* Packing glands are tried and true and as long as a little wet in the bilge doesn't bother you, why change, but if it does the dripless systems work well, IMHO.

 

[rednev]

I seem to recall the reason given for the loss of a florida bay coaster was something* coming loose in the er and tearing the bellows on the dripless shaft seal.
*True things shouldnt be flying around in ruff weather but murphy does crew on every boat .

 

[RickB]

Delfin wrote:

*I'm not sure what the panic is.*


*

I don't think anyone is having a panic attack. It has been a rather mild discussion about a piece of what I would call "elective" equipment and its virtues and faults.

Like I said, I wouldn't choose to replace a bulletproof piece of equipment with something that has a failure mode that is all but certain to lose the vessel, nor would I install one.

*

 

[Capn Chuck]

We installed the dripless system on Beach House and I have installed hundreds of them over the years. Each time this discussion comes up a parade of information is presented about sinking of boats due to dripless failures and pretty much all of that information is a repeat of something that happened years ago under actual circumstances we know nothing about. As a tech for a very large power and sailboat dealer we have had every new boat come in with the dripless system. Of all of the installations I have done and the boats I have been involved with we have seen no failures ever and on some systems that were over ten years old. We do not check our dripless every hour, every day,and maybe once a month. And when we do check it there is never anything going on. Now we are not stupid and we are always safety oriented in every installation we do. Directly under the dripless is a float switch that is attached to an alarm that can be heard in the next state. So that is why I don't need to constantly do inspections and our second bilge pump is nearby to handle water intrusion from there or any place else. This is one of those decisions that needs to be made by the skipper depending on there preferences and comfort levels. For those that think they are a disaster waiting to happen, by all means keep it off of your boat, since it is your boat. For those of us that like the system for our own reasons and preferences, install the units or leave them in place. I would never let the fear factor drive me to spend needless money and make changes to the boat, but then that is just me. Some of us have to make our own decisions when it comes to equipment. Too often when we come to these boards for info, what we get are the opinions and prejudices towards certain equipment, boats or whatever, rather than first hand feedback that will allow us to make informed decisions. The PSS system is one piece of equipment that generates this kind of discussion. Chuck

-- Edited by Capn Chuck on Thursday 21st of January 2010 12:40:48 PM

 

[Phil Fill]

I agree the dripless has pluses and minuses just like the old stuffing box.* Its not like the bellows are just going to fail, if you check on them every time you pull just the old one.* The bellows should/would show some sign of leaking/weeping.* I have blue paper towels under the dripless so if there is one drop it will be noticed when the boat is docked/stopped.* If it did start leaking I would take Saharan/plastic wrap stuff it in the hole to make a temporary plug and/or wrap the plastic around the bellows which should stop or at least slow the flow.
*
Another reason I installed is the dripless is more forgiving if the shaft is tweaked/bend.* The bellows can move up and down about ½" and still hold a seal.* I also installed double 3700 gph bilge pumps with alarms plus have a portable 2000 gph bilge pump, which should more than keep up with the flow.** I am more concerned about the 2" DD 671 raw water hoses leaking/braking as they are under pump pressure, where as the water pressure on the bellows is small in comparison.
*
Our bow thrust blew hole, so I took Saharan/plastic wrap stuff some in the hole wrapped it with the plastic wrap and duct taped.* Lasted 2 day until we could get pulled with no leaks as it was 2 ft under water with little water pressure.* *Also installed two 3700 ghp bilge pumps in the bow. **So weigh the pros and cons and if concerned have checked every time you*are in *the einge room, have checkevery time you*pull, install extra bilge pumps which can not hurt, and have a back up plan as stuff happens.*



-- Edited by Phil Fill on Thursday 21st of January 2010 12:42:55 PM

-- Edited by Phil Fill on Thursday 21st of January 2010 12:44:42 PM

-- Edited by Phil Fill on Thursday 21st of January 2010 01:08:32 PM

 

[motion30]

Capn Chuck wrote:

We installed the dripless system on Beach House and I have installed hundreds of them over the years. Each time this discussion comes up a parade of information is presented about sinking of boats due to dripless failures and pretty much all of that information is a repeat of something that happened years ago under actual circumstances we know nothing about. As a tech for a very large power and sailboat dealer we have had every new boat come in with the dripless system. Of all of the installations I have done and the boats I have been involved with we have seen no failures ever and on some systems that were over ten years old. We do not check our dripless every hour, every day,and maybe once a month. And when we do check it there is never anything going on. Now we are not stupid and we are always safety oriented in every installation we do. Directly under the dripless is a float switch that is attached to an alarm that can be heard in the next state. So that is why I don't need to constantly do inspections and our second bilge pump is nearby to handle water intrusion from there or any place else. This is one of those decisions that needs to be made by the skipper depending on there preferences and comfort levels. For those that think they are a disaster waiting to happen, by all means keep it off of your boat, since it is your boat. For those of us that like the system for our own reasons and preferences, install the units or leave them in place. I would never let the fear factor drive me to spend needless money and make changes to the boat, but then that is just me. Some of us have to make our own decisions when it comes to equipment. Too often when we come to these boards for info, what we get are the opinions and prejudices towards certain equipment, boats or whatever, rather than first hand feedback that will allow us to make informed decisions. The PSS system is one piece of equipment that generates this kind of discussion. Chuck

-- Edited by Capn Chuck on Thursday 21st of January 2010 12:40:48 PM

Chuck
** My boat is simular to yours. In replacing the stuffing box how did you suppot the stern tube?Is this instillation covered in your blog?* Thanks

*

 

[Capn Chuck]

We did cover it here with some photos,
[url]http://tinyurl.com/y87qagq[/url]
Chuck

 

[motion30]

The problem is I can not get the packing to live. Looking at Chucks blog I maybe know why. I have a set up simular to his except my stuffing box has NO water feed. Is a water feed normal on a trawler with a stern tube My stern tube is below the water line but 53'' from the cutlass bearing. Running down the ICW for 10-12hrs a day I have to tighten the packing gland every day ,then after 2 weeks or so the packing is mostly gone and needs replacment I have tried several types of packing with no real difference Is a water supply to the packing the solution?

-- Edited by motion30 on Thursday 21st of January 2010 03:50:46 PM

 

[motion30]

The shaft was out of the boat 2 years ago* It was straight at that time My marina checked the aligment 2 months ago and stated it was OK said the shaft looked good as well But there is a problem No unusual viberations as far as I can tell The marina also said I should have a rag joint at the flange Where to start?


-- Edited by motion30 on Thursday 21st of January 2010 04:46:20 PM

 

[Marin]

motion30 wrote:

I have tried several types of packing with no real difference Is a water supply to the packing the solution?

I don't think so.* Some boats with conventional packing glands (like ours) have water feeds and some don't.* Whether they do or not is dependent upon how much water gets back up into the shaft log when the boat is underway to cool and lubricate the cutless bearing(s) in the log.

From your description it sounds as though your packing material is shot unless there is some other problem--- alignment, vibration, bent shaft, etc.--- as fishboat described.

*

 

[Capn Chuck]

We had a similar problem with our previous boat and the exact same stuffing box as the trawler. We also found that using the trawler always required some adjustment to the stuffing box after running for a while. So that is why we decided to switch to the dripless system. You may find the problem is in the adjustment bolts which tend to loosen after running for a while and have nothing to do with the packing. Chuck

 

[Marin]

Capn Chuck wrote:

You may find the problem is in the adjustment bolts which tend to loosen after running for a while and have nothing to do with the packing. Chuck

If your stuffing box is fitted with a large adjustment nut that completely surrounds the entrance to*the stuffing box, there should be two of these nuts together.* On our boat the rear one is the locknut and the front one is the actual packing adjustment.* We've owned our boat for almost twelve years and had the packing changed once, about two years ago when we had the shafts out.* Between buying the boat and two years ago the packing nuts on one shaft need adjusting once and the nuts on the other shaft never needed any adjustment.* After the boxes were re-packed two years ago, there was a period of trial-and-error adjustment to get the right shaft log temperature but once that was accomplished we have not had to touch the adjustment on either shaft*since.* So what you are experiencing is not normal at all in*our experience.*

If your boat has this "large nut" arrangement but does not have the second, locking nut, that could be the source of the problem since the adjustment nut could easily back off with vibration.

The other kind of packing adjustment I have seen is a collar that fits around the stuffing box and is tightened down with a pair of smaller bolts on "ears" on either side of the collar.* I do not recall if this system uses lock nuts or not--- I would think it would.

 

[Marin]

oldfishboat wrote:

Marin Invader no 1 has the two bolts either side for adjustment. Man is it ever nice compared to the big nuts* < grin >. And yes they have locking nuts.

I can see where the two-nut system like yours is easier to deal with than the large nut system like we have.* In our case I slathered a ton of grease and anti-seize on the big*nuts so that when they do need adjustment they are at least a little easier to separate.* But in an area of limited space, which is the case on our boat, getting a large enough wrench on them is a real pain, and the little "packing gland" wrenches they sell for this purpose are next to useless.* Assuming the adjustment system you have is as effective as the "big nut" system, I woud prefer your system.

*