Badger
Well-Known Member
I have a tradional packing box and stern gland greaser on my Twister 28. I am thinking about fitting a deep sea seal. What are the pros and cons ? Thanks.
Deep sea seal versus traditional packing box and greaser
- Thread starter Badger
- Start date
sailorman
Well-Known Member
the trad one has worked for the past 35 > 40 yrs
Tranona
Well-Known Member
There are better seals available. The best seals (like a traditional stuffing box) seal radially around the shaft, whereas the Deep Sea Seal relies on a face to face seal.
The most popular non drip seals are Volvo, which is also low cost and fitted by many boat builders as original equipment or the Tides seal from US. Both of these use lip seals and are drip free.
Cloven
Well-Known Member
If you can, go for a Volvo seal. Brilliant bit of kit, easy to fit and maintenance free other than an annual grease and "burping" to release any trapped air if the boat has been out of the water.
They have a life span of 5years but I replaced my last one this year after being in service for 10 years without any drips or problems.
They have a life span of 5years but I replaced my last one this year after being in service for 10 years without any drips or problems.
Poignard
Well-Known Member
I've had a Twister for 12 years with a traditional packed stuffing box.
Cons? Can't think of any that would justify the bother of changing it. It is simple, gives no trouble at all and the only spare you need carry is a length of ptfe gland packing. If it started to fail [and in 12 years it hasn't] you would get plenty of warning instead of a possibly catastrophic leak.
Cons? Can't think of any that would justify the bother of changing it. It is simple, gives no trouble at all and the only spare you need carry is a length of ptfe gland packing. If it started to fail [and in 12 years it hasn't] you would get plenty of warning instead of a possibly catastrophic leak.
jason -and the arguenauts
Well-Known Member
Pros and cons. Well I guess that the two cons of the old fashioned stuffing box are that it leaks a bit when running and requires attention / maintenance on a regular basis. The cons of the lip seal type are that they wear a groove in the shaft after a few years
Currently I have a Volvo seal which is about 5 years old and leaking maybe a pint per hour running. Totally unacceptable but I may have to replace the 12 year old shaft as well as the seal.
Previously I have had the lip seal / oil bath type with a small oild reservoir. Theese are the best of the lot since the lip seals used are easy to replace and cost very little indeed.
Nobody in industry would dream of still using the old fashioned stuffing box.
Currently I have a Volvo seal which is about 5 years old and leaking maybe a pint per hour running. Totally unacceptable but I may have to replace the 12 year old shaft as well as the seal.
Previously I have had the lip seal / oil bath type with a small oild reservoir. Theese are the best of the lot since the lip seals used are easy to replace and cost very little indeed.
Nobody in industry would dream of still using the old fashioned stuffing box.
SteveIOW
Well-Known Member
I replaced my traditional greaser gland with a Deep Sea Seal 15 years ago. A big improvement. No more drips, adjustments or damage to shaft though overtightening. Would now like to replace the forward bellows section that clamps to the shaft but didn't think they were still available. Got my original from Halyard but they don't supply Deep Sea Seals now. Any suggestions on current supplier?
Tranona
Well-Known Member
Something seriously wrong if the shaft is wearing. How can a rubber seal wear a stainless steel shaft? Can understand the seal progressively failing and leaking if it is not regularly lubricated, but if the water lubricated part of the seal is wearing you would not be able to stand the noise it makes!
michael_w
Well-Known Member
If you fit a deep sea seal, beware of worn engine mounts.
I bought a boat fitted with one of these seals, the thrust from the prop pushed the engine forward and the seal opened; water got to well above the sole boards before I noticed!
Replaced forthwith with a traditional stuffing box and greaser. OK it may be old-fashioned and require maintainence, but it won't leak disastrously!
I bought a boat fitted with one of these seals, the thrust from the prop pushed the engine forward and the seal opened; water got to well above the sole boards before I noticed!
Replaced forthwith with a traditional stuffing box and greaser. OK it may be old-fashioned and require maintainence, but it won't leak disastrously!
jason -and the arguenauts
Well-Known Member
Its counter intuitive isnt it, but its a fact of engineering life that its the softer material that often wears the harder one. If you took your car engine to bits and looked at the crankshaft where it goes through similar lip seals you would find exactly the same effect. Indeed you will find the same effect with the water lubricated shaft bearing.
Poignard
Well-Known Member
It isn't the rubber that causes the wear but the tiny bits of abrasive material that become embedded in the rubber.
My engineer father used to tell a tale of a factory he visited in the days when machine tools were driven by line shafting and illumination was by incandescent lamps suspended on flex from the ceiling. One of the machine tool operators had flipped his light over the line shaft so as to get the light in a more convenient place. Over many years the flex had worn a groove in the rotating line shaft but the flex had not worn through.
My engineer father used to tell a tale of a factory he visited in the days when machine tools were driven by line shafting and illumination was by incandescent lamps suspended on flex from the ceiling. One of the machine tool operators had flipped his light over the line shaft so as to get the light in a more convenient place. Over many years the flex had worn a groove in the rotating line shaft but the flex had not worn through.
Refueler
Well-Known Member
Are you sure about that ? I can think of a few that still use trad. packed seals and for good reason.
Personally I would love a dripless / maintenance free stern seal - but until I find one that I like the look of - I'll stick with my 35+ yr old packed seal that has a turn or two of grease applied each time used, never needs 'burping' etc. etc.
I can even change packing while afloat ... can you replace any part of dripless while still afloat ? Safely that is ?
aquaplane
Well-Known Member
Nobody in industry, well the chemical industry which is where I have experience, want's to change to mechanical seals. They are complicated, expensive, difficult to set up, and prone to catastrophic failure.
Stuffing boxes, are messy, easy to maintain, fairly foolproof (but there are a better class of fools thesedays), can be jury rigged to get you home in an emergency, but leak a bit, sometimes. It's the nasty chemicals we are using and the need for containment that pushes us to the extra expense of machanical seals.
Sea water isn't nasty in small doses.
Malish
Well-Known Member
PSS seals always seem to get better reviews / less reports of failure than Deep Sea Seals
Tranona
Well-Known Member
But they can still fail catastrophically because of their design. The seal relies on the pressure of the bellows keeping the faces in contact. If that goes (see the post above on failure of Deep Sea seal) water pours in. If not set up properly as per the instructions they could fail simply through fore and aft movement when going into gear. Engines on very soft mounts can move enough in normal use.
The big advantage of radial seals (including stuffing boxes) is that they wear progressively
Conachair
Guest
I have had good results with trad stuffing box and ptfe packing from here http://www.asap-supplies.com/ Barely a drip and only had to tighten once in 3 years. Substantially cheaper than a new seal 
pampas
Well-Known Member
This is perfectly normal for a soft material to wear a harder one, the correct method is to fit a expendable sleeve. most of us would complain of the cost replacing these sleeves if fitted although in the long run,would save us thousands, eg new shaft if it not conveninent to shorten. With my engine the shaft has to slide due to gear box contruction, the inboard stuffing box nigh on impossible to reach. so I made and fitted a oil seal, with a sleeve for the running surface.
Pye_End
Well-Known Member
Whilst the Deep Sea Seal had a reputation for failure I have not heard the same for the PSS seal. Whilst comments about 'catastrophic failure by design' may well be true, are there any stories or numbers on this?
The advantage of the PSS over the Volvo it seems to me is that the PSS does not need burping. If you have poor access to this part of the boat then 'maintenance free' is a big advantage.
Tranona
Well-Known Member
"Statistics" are very difficult to come by for any kind of failure. There was however, a post on one of the forums about a year ago of a boat (quite a large Hunter) for sale in Florida which had sunk at its mooring because of failed face seal. There were also some rather dubious fugures produced by a magazine in the US suggesting sinkings through stern gland failure were quite common - but not really verifiable.
There have also been reports of build up of scale on the faces, causing wear, particularly if the boat is not used a lot.
I like the design of the Tides and the Vetus, as well as one or two of the oil filled seals that have been offered in the past. However they are very expensive compared with the Volvo seal which to mind is a masterpiece of robust simplicity, but accept that burping may put some off, although it only needs doing if the boat is dried out. If necessary it may be possible to organize a positive water feed that overcomes that problem.
tillergirl
Well-Known Member
Well there dear Badger you have it. Fit a modern seal and you can have great fun participating in posts on these fora. You can replace it every 5 years to keep the marine industry in business, you can burp it everytime you relaunch. You also get the chance to worry about premature catastrophic failure and the impact of worn engine mounts.
Or you could just leave well alone and enjoy the worry free experience of a traditional (you see no one could fit one of those to a new boat could they just because of the name) stuffing box which once properly set up will outlive you. TG's is currently 45 years old - no wear on shaft, no great puddle in t'bilge and nothing to worry about.
Or you could just leave well alone and enjoy the worry free experience of a traditional (you see no one could fit one of those to a new boat could they just because of the name) stuffing box which once properly set up will outlive you. TG's is currently 45 years old - no wear on shaft, no great puddle in t'bilge and nothing to worry about.