shaft seals

[ColinR]

I have a Deep Sea seal which is working perfectly but quite old so prudence suggests replacing it. I was thinking of a Tides Marine shaft seal. Does anyone have any experience of these good or bad they could pass on, or other types? I think I will go for a no maintainance one rather than a traditional stuffing box as it quite difficult to access to tighten up. Many thanks

Colin

 

[slimted]

I am also replacing my Manecraft DSS. The spec sheet specifies that water injection must be used on the new model, although an engineer told me they work fine without but would not put it in writing! Do you know if the Tide Marine seal needs water injection? Did you have water injection on the old DSS?
Good luck with it.

 

[pvb]

Volvo Penta rubber seal...

Many people consider that the Volvo Penta rubber seal is the simplest and most effective product.

 

[Guest]

I personally do not like any hole that big protected by non-reinforced rubber. I have described before the Alaskan cruisers adventure diving INSIDE his boat when the tube failed.

However, some boats were not designed for anything else. So far I have only ever recommended a PSS seal. I have even witnessed one after a life threatening manoeuvre requiring sustained high revs to escape a grounding in high winds, BUT with no water cooling. Other than quite a lot of black graphite everywhere, there were no problems, it went on to travel the world.

This seal has two fundamental difference to the PSS or Deep Sea.
1. The seal area is smaller compared to particle size of silt. Coral and some silt destroy engine water pumps and seals. It is the same water injected here.
2. The lip seal requires the existing shaft as one of the surfaces. I would need a new shaft.
3. The radial alignment of a lip seal requires a much closer tolerance. It requires a internal alignment bearing.
4. The axial location of the seal on the shaft is variable depending on the pressure of water in the rubber tube.
and the direction of the engine movement on its mounts.

The down side of the PSS is the thermal expansion can work the metal ring loose but there is an easy and fail safe solution.

Either way there is no such thing as a "no maintenance" shaft seal. Only a "no adjustment" shaft seal. All shaft seals need maintenance inspections. If the failure mode is a sinking situation, they need far more maintenance inspections than an old style fixed packing that just get hot or drip.

 

[jerryat]

Re: Volvo Penta rubber seal...

[ QUOTE ]
Many people consider that the Volvo Penta rubber seal is the simplest and most effective product.

[/ QUOTE ]

Agreed! Definitely the best and simplest shaft seal on the market!

I simply can't understand why people still bother with the other types which are far more expensive and not as effective long term.

 

[clyst]

You wont say that if a DSS fails !!! As happened to me recently /forums/images/graemlins/frown.gif. Bloody scarey . I'v now gone back to the good ol' stuffing box and sleep soundly in the knowledge that water tight integrity is not solely relying on two mating rings pressing together .

 

[robbieg]

Just replaced my Deep Sea Seal with a PSS. Other options I'm sure are fine. Personally the Volvo seal had a couple of downsides:

1. The seal rubs on the shaft-so your shaft needs to be ok so as not to damage the rubber seal.

2. You have to grease the seal every year & remember to "burp" it when launching-not a great hardship but having had a boat full of water when a yard launched my boat & forgot to burp the DSS seal I was looking for something that avoided this.

The PSS seal in my view is well engineered, does not make the seal on the shaft and with an air vent fitted (just a pipe above the waterline) to bleed air does not need burping. About £50 more than the Volvo seal I believe but I'm happy with my choice & no water in the boat!

 

[Mudplugger]

Try running a DSS on the E. Coast, has a life of about 2 years, before the mud in suspension knackers it!... I,ll third the comments about the Volvo seal...Simple, reliable, effective and unusually for Volvo, sensibly priced.

 

[JimC]

I'm in a similar position in having a Deep Sea Seal which is about 5 years old and still working well, and I'm based in Morecambe Bay where the water is as silt-laden and abrasive as it gets, or so I would think. The Volvo seal seems well thought-of but would you have to 'burp' it every time the boat dried-out and the stern tube emptied? For someyone who leaves their boat on a drying mooring this would clearly be impossible.

 

[doug748]

I have also been happy with the PSS. The Volvo job is only available in metric prop sizes, I understand.

 

[ridgy]

I've just had a PSS fitted and it's great. The engineer wasn't very enthusiastic about fitting a Volvo (my idea) and said he's never had any comeback from a PSS and he fits about 2 a week.

ASAP have them on special offer at 113+Vat.

 

[ColinR]

Many thanks for all this feedback. Where do I get a PSS seal?

Colin

 

[ColinR]

My DSS does not have water injection but you have to prime it with water when launching. The spec on the Tide marine one shows water injection. Cheers

 

[Robin]

We inherited a DSS (Deep Sea Seal) with our boat which looked flimsy and already had a small split in the belows. We replaced it 3 years ago with a PSS which is IMO much more robust and has a larger seal face allowing for more engine movement especially with soft mounts. The solid S/S collar which fits to the shaft and seals to it with 2 lip seals sets up perfectly at 90 degs to the shaft to allow consistent contact with the rotating face, unlike on the DSS where it is very difficult to get the standing part square to the shaft, especially given awkward access as in our case. The lip seals BTW do NOT rotate so do not wear, they are merely there as a (double) seal between the shaft and the S/S collar.

We were advised to buy the version of PSS with a water inlet but for normal use (not high speed) to simply use this to take off a length of hose to above the waterline. This provides a small head of water to keep the seal wet in the event of a venturi effect sucking water out of the stern tube a la dinghy bailers and after liftout/in automatically bleeds off any air trapped.

See Here PSS Seal Webpage

I bought ours from Lake Engineering in Poole. Lake Engineering Poole

 

[jimg]

Re: Volvo Penta rubber seal...

[ QUOTE ]
Many people consider that the Volvo Penta rubber seal is the simplest and most effective product.

[/ QUOTE ]

I have had 2 motor boats fitted with these and have had absolutely no problems. In a 20-25kt motor boat over hundreds of hours they have worked perfectly.

 

[Birdseye]

Re: Volvo Penta rubber seal...

Took a trip on a container ship a couple oy years ago and was interested to see that her shafts were sealed with lip seals. These are of course the standard technology in cars, trucks busses - and I've found they work very well in boats. They are maintenance free, though after a fair number of years use you may need to sleeve the shaft because of wear.

Why people still use the crude old type stuffing box I do not know.

 

[LeonF]

I am no technician. However some years ago I was attempting to buy a boat that the surveyor uncovered had been under water twice, possibly from a gland malfunction. His opinion was that Deep Sea Seals are fine on fishing boats that are in regular use, but on leisure boats where they may sit for a week or more then be sprung into action, they can malfunction or even rip.
I currently have the Halyard oil bath system. No longer made. Works fine but I do try and keep a regular eye on it and make sure it is not consuming oil (it shouldn't). Have always heard good things about the PSS.. try a search there has been lots of discussion in the past.