Leaking stern gland issue

[Guest]

Thank you. Very reassuring for those of us who will need to change the seal at some point.

[RLWP]

That's an excellent report John.

 

Richard

[bizzard]

I told you it wouldn't leak much water in.

[JohnDean]

I told you it wouldn't leak much water in.

Indeed you did! That's why I listen to those with actual experience and don't get spooked by those who haven't. It's really easy to be put off doing anything like this when your first contact with the supplier is a very negative one and there are dire warnings from people who've not had one of these apart in the water. It also doesn't help that the boatyard didn't even recognise the type, said they couldn't repair it and it would be better to fit a completely new unit of a different more common type!

Still, a bit of research, help from people like your good self and a healthy dose of common sense and here we are with it sorted out without difficulty. It doesn't say much for the boatyard, does it.

[Guest]

I am surprised that a boatyard said that they couldn't fix it. These Vetus glands (love 'em or hate 'em) have been around for many years now. The one in my boat is now ten years old, and I suspect it is ready for changing.

All I have ever done is inject silicon grease into it whenever I change the engine oil, and kept an eye on the engine mounts. It does drip a tiny bit when reversing long distances; always did from new.

[by'eck]

I have the same set up and I'm sure when I investigated the workings of this type of seal, that the water for lubrication comes in along the prop shaft and the tube is to take the water away so there is always cool water flowing around the seal. If you have like myself and many others the bottom plate on the weed hatch lid will stop water filling the weed box and coming down the pipe

 

Unlikely since the shaft entry behind the prop will be a low pressure in forward. Affirmed by Catweasel's comments that his only leaks in reverse. Its also the way the water lubricated Cutless bearing worked on my last sailboat, with forward facing skin fitting feeding via pipe to shaft housing immediately behind stuffing box, with water exiting at prop end.

 

I agree with your scepticism regarding feed from weed hatch though.

[Pete & Helen]

 

Unlikely since the shaft entry behind the prop will be a low pressure in forward. Affirmed by Catweasel's comments that his only leaks in reverse. Its also the way the water lubricated Cutless bearing worked on my last sailboat, with forward facing skin fitting feeding via pipe to shaft housing immediately behind stuffing box, with water exiting at prop end.

 

I agree with your scepticism regarding feed from weed hatch though.

 

I'll have to have a closer look when I have it out of the water in a couple of weeks time and see if there is anything to be seen forcing water in.

[Guest]

Vetus told me that the tube to the weedhatch (in the case of an NB) is a vent pipe. I imagine this is to "burp" air out of the seal, a bit like has to be done manually on the Volvo unit when a boat has been drydocked. I understand that at low canal speed there is enough water to lubricate the seal without having to introduce a flow.

From what I have read about the type with a carbon disc/bellows (name forgotten) these too use a similar venting system for displacement speed boats.

[bizzard]

 

I'll have to have a closer look when I have it out of the water in a couple of weeks time and see if there is anything to be seen forcing water in.

I'd say that the idea is to hope that a slight vacuum will be causedin the fluted rubber sterntube when going forwards and so will suck water from the weed box providing the tube fitting is fitted below the boxes waterline. When stationary or going astern this vacuum would cease and water should run up the tube from the propeller end. If the tube is above the boxes waterline it can only really serve to break any airlock in the tube which might prevent water running up and starving the bearing of water lubrication.

[Pete & Helen]

Ok, after much thought and all your good advice I can now report that the job has been done and it was very easy indeed and not at all alarming.

The 'Cassette' with the two seals in it was bought from Vetus for just over £100 delivered which wasn't too expensive. It's the 35mm size for this boat, that's the size they normally fit to wide boats by all accounts. It was out of stock but took less than a week to arrive.

The flexible engine coupling is of a type that doesn't use a key, it relies on friction alone on the plain shaft.

The four bolts were slackened and I managed to twist the propeller shaft out of it with a bit of effort. I was expecting that to be much more difficult. With hindsight, I should have slackened the four bolts that go to the flexible cross element of the coupling too, it would have made life easier. I only discovered this when I couldn't easily re-insert the shaft. It started easily enough, but there's obviously a slight misalignment else it would have gone on as easily as it did with those up tight.

The propeller shaft have clearly been cut to length with some kind of disc grinder, and the edges were razor sharp. I rounded them off with a file and emery paper until they were nice and smooth. A trial of the new seal on the shaft showed how easy it was to get on so there was nothing for it but to have a go.

The instructions mentioned an assembly sleeve, but that hasn't been included in the kits of this size at least for some time. I've fed this back to Vetus. Since there's no key on this installation, it wouldn't have been needed anyway.

After taking off the three Allen Cap screws on the old seal and breaking the seal, there was very little water indeed escaping. You could have left if for an hour and it wouldn't have been a problem. A cup full every minute at the most.

I'd already greased the shaft with the grease supplied and put the bulk of the tube in between the two seals. They say fill it to about 50%, and that's about all the grease you get anyway, it's not a big tube. I kept a little back to add later but I need to get another tube really.

Slipping the old one off and putting the new one on was very quick and easy. There's an 'O' ring instead of a gasket on this size, but the 'O' rings is about the same diameter as half way down the taper of the mating face. It wasn't clear how to line that up really. I greased it and inserted it into the fixed part of the stern tube and it seemed to stay in the middle. Whether there's a proper register for it is hard to tell, I couldn't get close enough to get a look. Anyway, offering up the cartridge with just a gentle pressure was enough to completely stop the water so I presumed the 'O' ring was located correctly.

That all tightened up with the three Allen Cap screws and now there's no sign of a leak.

Now I've got the old one home, I can see that it hasn't got the slightest hint of grease on it, so I can only assume that it was installed without any. It's no wonder it failed!

Anyway, all's well that ends well, and I thought it only fair to report back and to pass on what I learned. This isn't a scary job at all, and you shouldn't be spooked by any of the doom and gloom merchants who think there's going to be a Tsunami when you remove the seal. (other stern tube designs may differ!)

 

Did you do any realigning of the engine when refitting the prop-shaft into the coupling?

I'd say that the idea is to hope that a slight vacuum will be causedin the fluted rubber sterntube when going forwards and so will suck water from the weed box providing the tube fitting is fitted below the boxes waterline. When stationary or going astern this vacuum would cease and water should run up the tube from the propeller end. If the tube is above the boxes waterline it can only really serve to break any airlock in the tube which might prevent water running up and starving the bearing of water lubrication.

 

The tube is well above the normal water line in the weed box

[bizzard]

 

Did you do any realigning of the engine when refitting the prop-shaft into the coupling?

 

The tube is well above the normal water line in the weed box

Ok to break any airlock. I've seen em above and below the boxes waterline and I came to the conclusion that a lot of builders weren't sure what they were about.

[Guest]

The tube to my weedhatch is above the waterline, definitely. I checked it out because had it been underwater, I would have stipulated a shut off valve were fitted, like t'other end.

[JohnDean]

Gosh, that's a lot of feedback.... I'll try to address all the issues as well as I can from what I discovered.

 

Firstly, there's only a flat plate covering the top of the weed hatch, no extension and a flat plate above the propeller.

The outlet of the small pipe is a very long way indeed above the water level, there's no way you would put something in that position if it was supposed to be taking in water. This is clearly a vent. Without it, I suppose it's possible that water could be prevented from reaching the first seal and it needs that for lubrication. There are a key couple of words in the instructions that call the large rubber hose connecting the fixed part to the seal the 'Water Feed Pipe', that's a big clue. Presumably the function of the vent is to allow the water to rise up it until it's level with the water outside. This will mean that as the pressure varies due to the action of the propeller, the level will change but the area around the seal will remain full. This all makes sense to me. Cooling is irrelevant in these terms, there's no significant heating on the bearing or the seal that would not instantly be conducted away by the water and metal parts.

 

The engine mount is very flexible, and the coupling is fairly compliant too. I don't think the alignment is that bad else I wouldn't have been able to get the propeller shaft out while the four bolts to the flexible piece were still tight. I think it's probably not far enough out to warrant any further attention.

 

As far as I can see, the only way to check the alignment properly would be to remove the flexible piece from the centre of the drive coupling and then use a dial clock attached first to one coupling flange and then the other. It would be possible to determine not only the height difference in the middle of where the flexible coupling would be, but also the relative distances between the flanges at four points of the compass. With a little ingenuity you could figure out what angle and offset the engine had to the stern tube. Do bear in mind though that the propeller shaft will only be in the nominal centre of the stern tube, wherever it naturally sits due to the pressure of the seals. You can very easily displace it some distance in either direction so going overboard about accuracy is a bit meaningless. You'd have to force the shaft in each direction and measure those positions from some reference point before you could be sure of where the true centreline is. Even then, would you be aligning it with where it's worn already?

I think that if the coupling goes together easily, and the shaft doesn't have to be forced to one side or there's an alarming amount of slack to be taken up when you tighten the bolts to the centre part of the coupling, then I'd leave well alone.

 

For your information, here's the repair procedure I've noted for the cartridge itself....

 

 

Repairing the seal cartridge...

 

The lip seal used in the cartridge is a rotary shaft seal 35x52x7, these being the dimensions in mm. The 'O' ring is 2mm section with an inside diameter of 56mm.

Both of which can be obtained from SimplyBearings.co.uk

The seals are not a tight fit and can easily be pushed from their housing with a screwdriver from the back. Make sure to fit both of them the same way round ie with the open end of the seal facing the inside of the cartridge.

 

 

 

Bear in mind that this is for a 35mm propeller shaft. Yours may be different. The seals are very cheap, less than £4 each, so knowing what I know now, I'd just measure the shaft with a pair of vernier calipers and do the same where you can see the outside of the black seal. Those two dimensions will probably determine what thickness the seal is going to be, and for that price it's worth a punt and just buying them. The seals need to be pressed in flush with something flat but it takes very little force. All this can be done while the seal is off the boat, it only takes a matter of minutes. Take out one seal at a time, then you could always put it back if you ran into difficulty.

Now I've got the spare, I've replaced the seals, bought new 'O' rings, and that can sit in the spares box in case there's ever a 'next time'.

 

I hope that's useful

[Guest]

Very useful indeed. I often wondered if it was a standard seal in the housing. Any chance of a photo or part no. of the seals?

 

I agree re. the alignment, and if yours was a long way out, it would drip. I made a "steady bar" to hold the shaft in place whilst setting alingment which is no more than an exhaust clamp, a piece of angle iron, and two g cramps. Once it is ceratin that the shaft is central to the tube, it is just a matter of setting the algnment as per a "solid" setup. Out of interset, does your setup have an R&D flexible coupling or similar?

 

Again thanks for reporting all this info back. When I first bought our boat with this stern gear I had doubts about it, but ten years on it has grown on me. Your reporting of easy repair and cheap seals has made me feel happier.

 

ps the water tube on my boat is just like yours, high up on the weed hatch chest. It is well above the water line and am told (by Vetus fitter) that it serves to vent the seal. That is sufficient for displacement boats it would seem.

Edited May 16, 2014 by Guest

[JohnDean]

If you go to this page, you can enter the dimensions of any seal you like and you'll get all the options. The originals are standard Nitrile ones, but Vetus must be a pretty large outfit because they've had their name added to the moulding. I expect they would tell you that they're special, but I'm certain that they aren't.

 

Just bear in mind that mine has a 35mm shaft, yours may be different. They go up in increments of 5mm, so just wrap a piece of paper round yours and mark off the circumference, divide by 3.14 and that will tell you what yours is.

 

http://simplybearings.co.uk/shop/index.php?cPath=19_4463

 

 

I think someone from here said it was an R&D coupling. It's pretty flexible.

 

You need have no worries about these stern tubes, in my opinion they are very sound in principle and less maintenance than most. I suppose the Vetus fitter ought to know what the tube is for, and that's what I would call it. There's no continuous flow through it, as some suggested. It just ensures that the gland is always full of water. It's nothing more complicated than that.

Edited May 17, 2014 by JohnDean

[valrene9600]

The seal size is on the seal it`s self. Mine is 30 47 7. 30 being the shaft size. 47 diameter and 7 the thickness. As has been said new seals about a fiver. Fit them in your old unit and your ready for any future needs.

Of course if really brave you could get the seals and swap them into your original unit. Means a bit more time of water coming in but it is not much if you swap them quickly. They do push out easy.

[Guest]

If you go to this page, you can enter the dimensions of any seal you like and you'll get all the options. The originals are standard Nitrile ones, but Vetus must be a pretty large outfit because they've had their name added to the moulding. I expect they would tell you that they're special, but I'm certain that they aren't.

 

Just bear in mind that mine has a 35mm shaft, yours may be different. They go up in increments of 5mm, so just wrap a piece of paper round yours and mark off the circumference, divide by 3.14 and that will tell you what yours is.

 

http://simplybearings.co.uk/shop/index.php?cPath=19_4463

 

 

I think someone from here said it was an R&D coupling. It's pretty flexible.

 

You need have no worries about these stern tubes, in my opinion they are very sound in principle and less maintenance than most. I suppose the Vetus fitter ought to know what the tube is for, and that's what I would call it. There's no continuous flow through it, as some suggested. It just ensures that the gland is always full of water. It's nothing more complicated than that.

Superb, thanks again.

The seal size is on the seal it`s self. Mine is 30 47 7. 30 being the shaft size. 47 diameter and 7 the thickness. As has been said new seals about a fiver. Fit them in your old unit and your ready for any future needs.

Of course if really brave you could get the seals and swap them into your original unit. Means a bit more time of water coming in but it is not much if you swap them quickly. They do push out easy.

I think mine is 30mm so I will take a note of that size, Thanks.

 

One last question then I will go away: Are these seals the type with no garter spring? Thanks

Edited May 17, 2014 by Guest

[ditchcrawler]

I'd say that the idea is to hope that a slight vacuum will be causedin the fluted rubber sterntube when going forwards and so will suck water from the weed box providing the tube fitting is fitted below the boxes waterline. When stationary or going astern this vacuum would cease and water should run up the tube from the propeller end. If the tube is above the boxes waterline it can only really serve to break any airlock in the tube which might prevent water running up and starving the bearing of water lubrication.

Whenever I need to go down my weed hatch there is always a vacuum when I break the seal on the lid. This is the weight of water that has filled the box while I have been travelling, dropping down.

[Grace and Favour]

If you go to this page, you can enter the dimensions of any seal you like and you'll get all the options. The originals are standard Nitrile ones, but Vetus must be a pretty large outfit because they've had their name added to the moulding. I expect they would tell you that they're special, but I'm certain that they aren't.

 

Just bear in mind that mine has a 35mm shaft, yours may be different. They go up in increments of 5mm, so just wrap a piece of paper round yours and mark off the circumference, divide by 3.14 and that will tell you what yours is.

 

http://simplybearings.co.uk/shop/index.php?cPath=19_4463

 

 

I think someone from here said it was an R&D coupling. It's pretty flexible.

 

You need have no worries about these stern tubes, in my opinion they are very sound in principle and less maintenance than most. I suppose the Vetus fitter ought to know what the tube is for, and that's what I would call it. There's no continuous flow through it, as some suggested. It just ensures that the gland is always full of water. It's nothing more complicated than that.

JohnDean,

 

Great posts!

 

Thanks for that information - - - most useful!

[bigste]

This has to be one of the most informative threads I've seen on here, well done.

[Guest]

This has to be one of the most informative threads I've seen on here, well done.

Seconded.

[JohnDean]

Superb, thanks again.

I think mine is 30mm so I will take a note of that size, Thanks.

 

One last question then I will go away: Are these seals the type with no garter spring? Thanks

The ones on the original unit didn't have garter springs, but the type I bought did. I don't think there's an issue with either type. I think the ones without the garter just use more rubber to provide the grip on the shaft, that's all.

This has to be one of the most informative threads I've seen on here, well done.

You're most welcome. I think it's only fair to give something back when people have been so helpful. This repair has saved a lot of money and I'd like to think that someone else will now have everything they need to do the same without any major headaches.

Without all your help, I wouldn't even know what stern tube make is was, let alone get it all fixed. These places are gold dust if we all feed back what we discover.

[Guest]

The ones on the original unit didn't have garter springs, but the type I bought did. I don't think there's an issue with either type. I think the ones without the garter just use more rubber to provide the grip on the shaft, that's all.

Thanks, that's great I did wonder what the difference was.

Edited May 25, 2014 by Guest

[Pete & Helen]

If you go to this page, you can enter the dimensions of any seal you like and you'll get all the options. The originals are standard Nitrile ones, but Vetus must be a pretty large outfit because they've had their name added to the moulding. I expect they would tell you that they're special, but I'm certain that they aren't.

 

Just bear in mind that mine has a 35mm shaft, yours may be different. They go up in increments of 5mm, so just wrap a piece of paper round yours and mark off the circumference, divide by 3.14 and that will tell you what yours is.

 

http://simplybearings.co.uk/shop/index.php?cPath=19_4463

 

 

I think someone from here said it was an R&D coupling. It's pretty flexible.

 

You need have no worries about these stern tubes, in my opinion they are very sound in principle and less maintenance than most. I suppose the Vetus fitter ought to know what the tube is for, and that's what I would call it. There's no continuous flow through it, as some suggested. It just ensures that the gland is always full of water. It's nothing more complicated than that.

 

Thanks John for this thread you have saved me about £100. I toke my bearing out when i was in dry dock the went to simply bearings and got 2 sets for around £10, one to fit and one as a spare. I didnt have an "o" ring on mine just 2 bearings and a paper gasket.

Thanks again, just shows how great this forum can be. If we ever meet up then a beer is on me

[JohnDean]

 

Thanks John for this thread you have saved me about £100. I toke my bearing out when i was in dry dock the went to simply bearings and got 2 sets for around £10, one to fit and one as a spare. I didnt have an "o" ring on mine just 2 bearings and a paper gasket.

Thanks again, just shows how great this forum can be. If we ever meet up then a beer is on me

You're most welcome. You did get some of the right grease from Vetus to squirt in between the two seals though? Don't panic if you didn't just get plenty in there as soon as you can. I think the instructions say to fill it at least half full of grease. I don't think the one on mine ever had any grease so that's why I'm saying don't panic. I'm sure it won't hurt it to run for a little while without. I just had alarm bells going off in my head because you didn't mention the grease. They do say that it's important to only use their grease by the way. You can get it from their web site.