Space for PSS Seal?

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syvictoria

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Hi. We're installing a new Beta 25 in a Victoria 30. We had to cut out the old Yanmar as the prop shaft was seized into the coupling which in turn was seized onto the gearbox! Consequently we're also now replacing the prop shaft, coupling, and stern gland. We already have an R&D flexible coupling (came with engine) and we're planning on buying an R&D split coupling. This will leave 116mm of prop shaft exposed before it enters the stern tube which is currently visible to a length of 70mm. The boat originally had a traditional style packing gland with dogs to lock onto the stern tube. At some point during our efforts to remove the Yanmar, the dogs on the stern tube have broken off! We therefore need to make good the end of the stern tube, but my question is, can we remove a further 30mm to enable the fitting of a PSS shaft seal (177mm overall with 38mm over the stern tube, leaving a length of 139mm uncompressed required for fitting)?

An alternative would perhaps be a Volvo seal, but I can't seem to find the dimensions of the 25mm/42mm one anywhere. A further alternative would be to use a solid shaft coupling, which would be some 25mm shorter, rather than a split one, but I think going the split route is probably otherwise preferable?

Also, should we be concerned that the dogs sheared off the stern tube?!

TIA!
 
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doug748 said:
I have one of these seals. By my calculations (do check and measure three times!) it could just work. I have assumed that this is the model you would need/choose:

http://www.shaftseal.com/de/products/20

You would be relying, to a small extent, on the compression of the bellows to make the fit.
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The OP has already said there is not enough room even with the bellows compressed. The Volvo or Radice seals will fit comfortably and less than half the price.
 
Thanks for all the replies! The Radice seems to be the most popular solution, and to me it would appear to offer advantages over the Volvo. Are Sillette's the best (or even only?!) people to buy from in the UK? Can anyone comment on how they compare price-wise for propellers (3 blade 13x9 I think) and prop shafts (25mm by 600mm)? Thanks again.
 
Tranona said:
I have. Please explain how you can fit 120mm into a space 117mm long.

And my name is not Sam.
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I don't mean look at the words.

I mean read it and try to understand what questions syvictoria is asking. What help is this to the list of original queries:



"The OP has already said there is not enough room even with the bellows compressed. The Volvo or Radice seals will fit comfortably and less than half the price. "


The first sentence is untrue and the second the usual periperal waffle. Just try and help the bloke, try giving him a link to the sizes of the Volve seal, instead of carping and potboiling.
 
syvictoria said:
Thanks for all the replies! The Radice seems to be the most popular solution, and to me it would appear to offer advantages over the Volvo. Are Sillette's the best (or even only?!) people to buy from in the UK? Can anyone comment on how they compare price-wise for propellers (3 blade 13x9 I think) and prop shafts (25mm by 600mm)? Thanks again.
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Got mine from Sillette and found them helpful. Probably a good source of prop as well. Could also check out T Norris's prices. Make sure the quotes include an anti-singing edge.
 
I have fitted PSS seal and to get mine to fit had to cut about an inch of the stern tube, but then my tube is/ was quite long After a season I have been very happy with the set up. Being on a drying mooring I was fed up with burping the Volvo seal
 
pvb said:
He already has that, see post #2.
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Yes, good work - from you.


PS

What I did mean to say in my original post, well actually I did say it and then deleted it for some reason, was, I don't think I would recommend a PSS seal unless I could try it against the mocked up installation first, so you would need to get one on a return basis. Too much hassle, perhaps.

The other factor is access. If your chosen seal has to be burped, greased or whatever then you could have real difficulties with a small boat. This is worth thinking about, I don't know the Victoria well, if you have a cockpit hatch it will be no worry.
 
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Thanks again for the replies. Yes unfortunately the V30 does have reasonably limited access, however, the Radice doesn't, as I understand, require burping due to the vent/water pipe.
 
syvictoria said:
Thanks again for the replies. Yes unfortunately the V30 does have reasonably limited access, however, the Radice doesn't, as I understand, require burping due to the vent/water pipe.
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Not quite sure how far you are along the line but there are a number of options with the limited space you have. Very similar to my own installation so the following might help. Mount the engine as far forward as possible within the bay to maximise the space after of the gearbox coupling. To maximise the length of free shaft a fixed coupling is the shortest. If you want a flexible coupling the Bullflex at 85 mm is the shortest followed by an R&Design plus solid half coupling. One the things to aim for is enough clearance to change your seal without having to lift the engine or drop the rudder to get the shaft out. As has already been suggested the Volvo or Radice seals are the softest using 65mm shaft compared with 120 mm for the PSS. You need 110 mm minimum between the end of the shaft when it is pushed back and the gearbox coupling but you may not be able to do this without fouling the rudder, particularly if you fit a rope cutter which moves the prop back.

So, suggest you start with the engine in place, decide on the coupling and get the shaft made as the length will be different depending on the coupling and whether you have a rope cutter. You may be able to create enough room to get the coupling on and off and change the seal without moving the engine but suspect that it will be clearance to the rudder which will be the problem.

BTW burping is not a big issue unless you dry out regularly. More of a problem getting grease into the seals which makes slightly longer Radice the choice assuming they have asize to fit your shaft and tube.

Hope this helps.
 
Tranona said:
Not quite sure how far you are along the line but there are a number of options with the limited space you have. Very similar to my own installation so the following might help. Mount the engine as far forward as possible within the bay to maximise the space after of the gearbox coupling. To maximise the length of free shaft a fixed coupling is the shortest. If you want a flexible coupling the Bullflex at 85 mm is the shortest followed by an R&Design plus solid half coupling. One the things to aim for is enough clearance to change your seal without having to lift the engine or drop the rudder to get the shaft out. As has already been suggested the Volvo or Radice seals are the softest using 65mm shaft compared with 120 mm for the PSS. You need 110 mm minimum between the end of the shaft when it is pushed back and the gearbox coupling but you may not be able to do this without fouling the rudder, particularly if you fit a rope cutter which moves the prop back.

So, suggest you start with the engine in place, decide on the coupling and get the shaft made as the length will be different depending on the coupling and whether you have a rope cutter. You may be able to create enough room to get the coupling on and off and change the seal without moving the engine but suspect that it will be clearance to the rudder which will be the problem.

BTW burping is not a big issue unless you dry out regularly. More of a problem getting grease into the seals which makes slightly longer Radice the choice assuming they have asize to fit your shaft and tube.

Hope this helps.
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Thanks Tranona. Rather stupidly, I hadn't given as much thought to changing the seal as I should have done. Obviously if the boat's ashore, then we would be able to drop the rudder, but I now feel that we do definitely need the security of the knowing that we can change it in an emergency when there is no lift nearby. As we only have a maximum of 680mm from rudder to gearbox flange, and the prop shaft is going to be somewhere in the region of 580-600mm, this probably presents a bit of a problem. My vagueness on the overall length is due to the fact that I'm not sure whether or not the shaft ordinarily goes all the way through the shaft coupling, or is the flange solid, thereby reducing the length of the shaft by perhaps 1-2cm (I don't have my old one to hand)?

The only solution I can come up with at present (other than not installing a dripless seal that is!) is to use a bobbin between the R&D flexible coupling (which I already own) and the split shaft coupling, which would reduce the shaft length. Would that be a good idea please?
 
My post above has forgotten to take account of the width of the R&D flexible coupling (33mm)... Therefore, I may be able to fit in a Volvo seal (length 102mm) without a bobbin. It all depends on the gap between the shaft end and the rudder which I don't currently know for sure as I don't yet own the propeller!
 
Usually there is a stop inside the coupling and the shaft goes up hard against that. If it is a clamp coupling you may be able to rely on just the clamp but I have known them to move. Best way is to assemble the coupling on the engine in place on its mounts, push a broom handle usually 25 mm through the stern tube until it hits the stop in the coupling. Measure 15 mm from the back of the cutless housing and this gives the length of the shaft up to the start of the taper or the front of the prop.
 
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