Sealed stern gland vs traditional stern gland greaser

[MajorJones]

Hi all,

 

Considering having a sealed stern gland installed (the one that won't require manual greasing every evening) - are there any downsides to it? Are there any practical reasons not to have one and go with a traditional greaser?

 

Thank you!

[Francis Herne]

I have a PSS one on Lark Ascending.

 

A disadvantage is that you can't slide the shaft in and out while in the water, which makes changing the drive plate an all-day job and not a relatively simple one.

 

The other is that if it ever fails in some way I don't know how to fix it. Ordinary packed stern glands seem pretty straightforward. That said it's done 23 years and seems fine so far.

[Tony Brooks]

1 hour ago, Francis Herne said:

I have a PSS one on Lark Ascending.

 

A disadvantage is that you can't slide the shaft in and out while in the water, which makes changing the drive plate an all-day job and not a relatively simple one.

 

The other is that if it ever fails in some way I don't know how to fix it. Ordinary packed stern glands seem pretty straightforward. That said it's done 23 years and seems fine so far.

 

Can you not just release the rotor on the shaft with a PSS seal so you can slide the shaft. If I were to go for one, I think the PSS is the one I would choose.

 

9 hours ago, MajorJones said:

Hi all,

 

Considering having a sealed stern gland installed (the one that won't require manual greasing every evening) - are there any downsides to it? Are there any practical reasons not to have one and go with a traditional greaser?

 

Thank you!

 

You do realise that you will have to change the shaft bearings to Cutless rubber ones that are water lubricated. That may or may not be a problem, depending upon how gritty the water you boat in is. No regular supply of grease to push any grit out of the bearings, but many seem to be fine with them on canals.

 

No greaser means that you can't fill the gap between shaft and tube with grease as a temporary seal or use strips of old fabric, well greased, as an emergency packing if the seal failed.

 

PS The PSS seal is a carbon ring, so does not need any greasing, but the Vetus and Volvo glands do, just not as much grease (except it use a special grease), and at far longer intervals than a conventional gland.

Edited June 19, 2023 by Tony Brooks

[fatmanblue]

I've had a Vetus one for twenty years with no issues. A tiny bit of silicone grease added once a year. No drips, lovely dry bilge.  I would definitelyhave another.

[blackrose]

9 hours ago, MajorJones said:

Hi all,

 

Considering having a sealed stern gland installed (the one that won't require manual greasing every evening) - are there any downsides to it? Are there any practical reasons not to have one and go with a traditional greaser?

 

Thank you!

 

Just to clarify for my benefit, by "sealed stern gland" do you mean water lubricated stern gland or is this something else?

 

If you mean the water lubricated type they are not sealed and require a flow of water through the cutless bearing. 

 

I've had the Vetus water lubricated stern gland on my boat for the last 18 years. I'd say they're pretty good and a lot less messy than a traditional greasy gland. There's also a Volvo water lubricated gland available. 

 

If you look at the installation instructions for the Vetus gland there are two installation options. One uses a water scoop fitting on the hull below the waterline and the other is plumbed into an engine's raw water cooling system. For canal boats travelling at canal and river speeds what some builders have done is install the water intake from a spigot above the waterline in the weedhatch. The idea is that the pressure in the weedhatch will feed the gland and it seems to work.

 

In terms of maintenance all I've ever done is lubricate the gland with plumber's silicone grease every year or so. Instead of trying to get the grease through a 3 or 4mm hole into the gland I take the front bronze housing off and slide it up the prop shaft and smear a load of silicone grease in. Water will come into the boat at the rate of about a litre a minute, but this might be beneficial in flushing any crap out of the cutless bearing.

[Tony Brooks]

2 minutes ago, blackrose said:

n terms of maintenance all I've ever done is lubricate the gland with plumber's silicone grease every year or so. Instead of trying to get the grease through a 3 or 4mm hole into the gland I take the front bronze housing off and slide it up the prop shaft and smear a load of silicone grease in. Water will come into the boat at the rate of about a litre a minute, but this might be beneficial in flushing any crap out of the cutless bearing.

 

It also gives you a chance to clean any scale off the shaft as per the Vetus instructions.

[Tracy D'arth]

I think I prefer the old fashioned stuffing box and greaser.

[David Mack]

This may be a valid question if you are having a new boat built, but if this is an existing boat, is the possible benefit of avoiding daily greasing worth the cost and hassle of getting the job done?

[MajorJones]

32 minutes ago, blackrose said:

Just to clarify for my benefit, by "sealed stern gland" do you mean water lubricated stern gland or is this something else?

Yes, I meant water lubricated - as in 'sealed/closed' vs 'open'. Sorry for the confusion!

 

Am I right to assume that everyone who has PSS/Volvo/Vetus stern gland installed would not go with the traditional greaser? Based on the answers so far, it does seem like the case - no more daily greasing for me then!

 

 

2 minutes ago, David Mack said:

This may be a valid question if you are having a new boat built, but if this is an existing boat, is the possible benefit of avoiding daily greasing worth the cost and hassle of getting the job done?

that's a new build!

[Tracy D'arth]

I don't find turning a greaser a bit after stopping the engine to be arduous at all.

 

If your non greased "sealed" water lubed silicone greased gizzmo fails you are stuffed.

If your greased, stuffed gland weeps, you tighten it a bit or if all else fails stuff in a bit of cloth or even newspaper and carry on.

[Tony Brooks]

Note that the PSS seal, and I doubt the others, are water lubricated. It is the associated shaft bearings that are water lubricated.

 

The Vetus and Volvo seals need greasing now and again, that does not suggest water lubrication. The PSS does not need water lubrication because the carbon ring is self lubricating, but the lack of greaser probably demands that the shaft bearings are water lubricated.

1 minute ago, Tracy D'arth said:

I don't find turning a greaser a bit after stopping the engine to be arduous at all.

 

If your non greased "sealed" water lubed silicone greased gizzmo fails you are stuffed.

If your greased, stuffed gland weeps, you tighten it a bit or if all else fails stuff in a bit of cloth or even newspaper and carry on.

 

My thoughts exactly, and we recently had a question about a permanently leaking Volvo seal - it seems a new shaft was required, but that can happen to packed glands, it is far easier to temporarily stop the leak on a packed gland.

[MajorJones]

35 minutes ago, Tony Brooks said:

Note that the PSS seal, and I doubt the others, are water lubricated. It is the associated shaft bearings that are water lubricated.

PSS is marketed as a maintenance-free solution, yes it is more expensive, but it seems like a better alternative to the water-lubricated Volvo/Vetus. Is that the case, or am I missing something? 

[Francis Herne]

2 hours ago, Tony Brooks said:

Can you not just release the rotor on the shaft with a PSS seal so you can slide the shaft.

Er... if I can, that would save me a lot of hassle.

Time to have another look at the manual!

[IanD]

Just now, MajorJones said:

PSS is marketed as a maintenance-free solution, yes it is more expensive, but it seems like a better alternative to the water-lubricated Volvo/Vetus. Is that the case, or am I missing something? 

No, it's better but more expensive which is why few canal boats use it but lots of yachties do... 😉

[Tony Brooks]

30 minutes ago, Francis Herne said:

Er... if I can, that would save me a lot of hassle.

Time to have another look at the manual!

 

I think it has a recessed grub screw, with the rotor sealed to the shaft by an O ring. If I am correct, I'm not sure how easily the O ring will slide on the shaft after  23 tears in the same place.

35 minutes ago, MajorJones said:

PSS is marketed as a maintenance-free solution, yes it is more expensive, but it seems like a better alternative to the water-lubricated Volvo/Vetus. Is that the case, or am I missing something? 

 

They are all MARKETED as maintenance free ------- until you read the manuals, but the PSS uses a carbon ring running on a rotor as the seal so really is self lubricating and long proven on car water pump (I expect now lip seals are used on cost grounds) and on clutch release bearings. The carbon will eventually wear out, but probably long after the lip seas would in other glands. I suspect it may also be more tolerant of slight shaft misalignment.

[Peanut]

On Katy Lou, I removed a Deep Sea seal and replaced it with a Tides Marine seal, similar to the Volvo seal.  Deep Sea seals can fail catastrophically, they supply a clamp to stop water ingress, but then you are not supposed to use the engine until fixed.

One surveyor preferred the conventional Stuffing Box as there is little to go wrong and it can be fixed easily even with shaft wear it won't sink the boat.

There is a review of shaft seals here:

https://www.pbo.co.uk/gear/dripless-shaft-seals-pbo-buyers-guide-17357

Lots on PSS seals, and others, on Yachting and Boating World.

 

 

[Thames Bhaji]

I have a pair of PSS on Lyra.  Just a couple of things to add…

- Although the carbon is kind of self-lubricating, they definitely need to be wet. You need to make sure there is a good enough supply of water behind them to prevent overheating. 
- I have always released the stainless rotor and slid it along when I’ve needed to pull the shaft back or forwards. It’s easy enough, and if it has stuck after many years I think a few taps with a wooden block would get it moving. 
 

[Morris]

I have a Volvo seal. Recently had the experience of travelling up a canal full of hair like weed which wrapped round the prop shaft and, judging by the sounds produced and the bubbles from the end of the Stern tube when the weed was removed, starved the seal of water.  This caused it to drip at quite a fast rate until I managed to get some silicone grease into it. It is still dripping at certain revs though so I imagine I need a new one. 

 

I would much prefer something I could easily grease and/or tighten and I'm thinking of getting a packed gland fitted. 

[MajorJones]

Thank you very much, everyone, for your comments! Very valuable and insightful, as usual!

I'm going with the Vetus solutions - it seems everyone's happy with it, and it's a well-known solution across boat builders and service people, so we won't have any issues servicing/maintaining it long-term.

[Bee]

Not much to go wrong with the old fashioned one and I always think that the stern tube which on Bee is quite a long one benefits through having a bit of grease inside it. I've never heard of a steel stern tube corroding through but a slug of grease in it every time I use the boat must help. Anyway, it's a boat so you are supposed to be covered in grease and mud.

[Sea Dog]

Purely by luck, I have a Volvo seal. I can't think how a stern seal could be simpler, lower maintenance or more reliable in a slow  speed vessel like a narrowboat. A bit of silicone grease every 200 hours keeps it happy (I'm still on the original tube, so even Volvo's own specialist silicone is hugely economical). Mine has never dripped a drop in 15 years except for when you deliberately squeeze it to "burp" the air out and ensure lubrication water is restored on relaunching after haul out.

I'd suggest the most likely failure mechanism would be to drip like a conventional greased gland. The water channels in a cutless bearing are so small that rag held around the shaft covering the cutless bearing would allow you to change it whilst in the water with very little water ingress in case of a failure in service, but it would surprise me if replacement ever needed outside of a docking period. No issue if you need to slide the shaft back for any reason - it comes with a little plastic sleeve with which to protect the lip seal. 

[Jen-in-Wellies]

27 minutes ago, Sea Dog said:

Purely by luck, I have a Volvo seal. I can't think how a stern seal could be simpler, lower maintenance or more reliable in a slow  speed vessel like a narrowboat. A bit of silicone grease every 200 hours keeps it happy (I'm still on the original tube, so even Volvo's own specialist silicone is hugely economical). Mine has never dripped a drop in 15 years except for when you deliberately squeeze it to "burp" the air out and ensure lubrication water is restored on relaunching after haul out.

I'd suggest the most likely failure mechanism would be to drip like a conventional greased gland. The water channels in a cutless bearing are so small that rag held around the shaft covering the cutless bearing would allow you to change it whilst in the water with very little water ingress in case of a failure in service, but it would surprise me if replacement ever needed outside of a docking period. No issue if you need to slide the shaft back for any reason - it comes with a little plastic sleeve with which to protect the lip seal. 

I'll second @Sea Dog's praise of the Volvo stern gland. We've both got Simon Piper boats and these are a common fitting on them. Bone dry and no problems in any conditions so far, including some shallow and muddy ditches.

[Bargebuilder]

8 hours ago, Jen-in-Wellies said:

I'll second @Sea Dog's praise of the Volvo stern gland. We've both got Simon Piper boats and these are a common fitting on them. Bone dry and no problems in any conditions so far, including some shallow and muddy ditches.

The Volvo 'dripless' seal is popular with some, but I inherited one when I bought a  second hand boat and it dripped, in fact spattered when the shaft rotated. Imagining it to be old and worn I had it replaced, which wasn't cheap. Upon launch it was 'burped' to ensure there was no trapped air and greased with Volvo's special grease. The shaft, prior to fitting the new unit was inspected and found to be in excellent condition. The new one also spattered water when the engine was in gear! Perhaps I was unlucky, but I never felt confident in the Volvo seal.

 

Do Volvo not recommend replacement every 5 years or 500 hours? I do 300 hours cruising in an average year, so Volvo would have me replace it every 2 years! It may last longer for many, but it if failed and the boat sank, I wonder what an insurance company would say if a claim was made.

 

The two lip seals that stop your boat from sinking are tough, but incredibly fine. They may spatter or drip with age or wear, especially in silty, abrasive water. Replacement may, for some people, need to be frequent and is expensive.

 

I've replaced mine now with an old fashioned stuffing box. No chance of a catastrophic failure, just a few drips of water into the tray beneath whilst motoring and completely dry when the shaft isn't rotating. Very easy and cheap to re-stuff every 10 years or so: I feel a lot happier now.

 

 

[Sea Dog]

2 minutes ago, Bargebuilder said:

Do Volvo not recommend replacement every 5 years or 500 hours?

They do say 5 years but then in a less forgiving environment with a high speed shaft and a long sea voyage from a mechanic I can see why they might cover their ass! Hardly the case in a narrowboat. Not sure about the 500 hour figure - why would they provide more than a finger full of grease if the only going to last 2 or 3 the service interval?

Mine (and @Jen-in-Wellies ) have lasted donkey's years with no issue. I think catastrophic failure is no greater than any other seal, and the failure mechanism is most likely a developing drip - unless the 200 hourly greasing is ignored. The gaps in the cutless bearing allowing water lubrication are pretty small, so hardly a deluge even if you took the boot off.

 

Expensive? I just did a quick Google and found it at £120, which has gone up significantly since I last looked, but hardly a lot to pay.

 

I'd say your second hand issue was more likely to be shaft related - maybe an imperfect surface or an odd size? Metric v imperial? I can see a perfect fit would be essential. More pertinent, perhaps, your mechanic did use the lip seal protector when sliding the new replacement for your old leaky one it onto the shaft, did he?

[Bargebuilder]

9 minutes ago, Sea Dog said:

Expensive? I just did a quick Google and found it at £120, which has gone up significantly since I last looked, but hardly a lot to pay.

 

I'd say your second hand issue was more likely to be shaft related - maybe an imperfect surface or an odd size? Metric v imperial? I can see a perfect fit would be essential. More pertinent, perhaps, your mechanic did use the lip seal protector when sliding the new replacement for your old leaky one it onto the shaft, did he?

By expensive, I meant £20 for a length of stuffing material every 10 years compared to £120 (plus labour perhaps) every 5 years for a Volvo seal.

 

I'm guessing that many people would pay someone to replace a Volvo seal, whereas re-stuffing a box is a quick, simple, diy operation.

 

I watched my new Volvo seal being installed and I can confirm that the seal protector was used, the shaft was in excellent condition and it was measured with digital calipers to make sure that the correct size seal was obtained; it still spattered water! It never failed, but I got fed up with it and lost confidence in it and after two years and 600 hours use, I had it replaced with a stuffing box. 

 

My stuffing box gets a turn of the greaser at the end of each day's cruising and the collar may need adjustment every two or three years. 

 

I have used PTFE stuffing and although the dripping is minimal, the box doesn't warm up. The bilge doesn't get wet because I have a small dish to catch the drips. There really isn't anything to fail and over the years it will be much cheaper than any 'dripless' seal.