Bobbin shaft connector to facillitate seal change

[pcatterall]

Yes I'm paranoid about seal changing!! After springing a leak on my lip seal and having to consider an expensive mid season lift out, rudder off and seal change when several of our 'owners group' had booked their summer sailing holiday. I know that many of you will say 'what's the problem my seal has done 50 years" etc etc. In the event we have held out to winter and our scheduled lift out.
We would still like to see if we could do this change in the water. I know that the water coming in from my cutlass bearing can be coped with no problem. Would it be possible to fit a Bobbin shaft connector on a shortened shaft so that items could be slid on and off the shaft?
Not sure if I could get a connector for the back of my Thames Marine gearbox but I could measure up and look into that.
Depending on how much of a struggle it is to separate my shaft from the existing solid connector I wonder if I should consider a split connector which would just separate to facilitate separation?
All advice appreciated!
Thanks guys

 

[vyv_cox]

In view of the struggles that people describe when trying to separate shafts from couplings, for a first try I would not even think of it, particularly if you are lifting out anyway. A second time I would give it a go. I have removed a gland on the water and found it amazing how effective a rag wound around the stern tube could be. AFAIK split connectors don't fall into two halves, the flange is solid but the tubular section has a cut or two in it. Makes the job a little easier but you will still have to push the shaft out. Lots of photos on the website, including the best method of pushing the shaft out of the coupling.

 

[rotrax]

Fit a Volvo or Radice seal.

 

[Lon nan Gruagach]

In view of the struggles that people describe when trying to separate shafts from couplings, for a first try I would not even think of it, particularly if you are lifting out anyway. A second time I would give it a go. I have removed a gland on the water and found it amazing how effective a rag wound around the stern tube could be. AFAIK split connectors don't fall into two halves, the flange is solid but the tubular section has a cut or two in it. Makes the job a little easier but you will still have to push the shaft out. Lots of photos on the website, including the best method of pushing the shaft out of the coupling.

Right, with R&D split couplings, about 1/3rd the length is solid, the remaining 2/3rds is split and has 4 clamping bolts. even then it is a very snug fit, however it will remain a very snug fit and not a cold welded fit as happens with tapers.

To remove old coupling slice it length ways as close to the shaft as you can. It may be that you wont need a bobbin extension.

 

[pcatterall]

Thanks guys.
I am not contemplating removing the shaft (this time round) while afloat but would like ( for reasons sated in my OP) to be able to do it afloat should I ever need to again.
Does the shaft have to penetrate all the way down a split coupling? Could it not just be fitted into the part that separates? If I could then remove the coupling completely there might then be space to remove and fit my spare seal. For the same reason does the shaft have to be inside the bobbin connector?

 

[Lon nan Gruagach]

Thanks guys.
I am not contemplating removing the shaft (this time round) while afloat but would like ( for reasons sated in my OP) to be able to do it afloat should I ever need to again.
Does the shaft have to penetrate all the way down a split coupling? Could it not just be fitted into the part that separates? If I could then remove the coupling completely there might then be space to remove and fit my spare seal. For the same reason does the shaft have to be inside the bobbin connector?

Really ought to, and, no.

If the shaft is not a good way, preferably all the way, in the split connector you will have really nasty stresses at the start of the split. On the other hand, the bobbin is a shaft extension and is designed to be the only part of the system at that point.

If you do decide to place the connector proud of the shaft end then you really should consider balance. Not that balance is that critical in a keyed shaft (it would have splines if it were that sensitive), I would cut a keyway in the shaft as long as the whole connector and use a key that same length