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If you told me I could strip the whole of the stern gear - flexicoupling, stuffing box, prop and shaft, stern tube and outer housing in two and a half hours - I would have laughed in your face. Still - that's the way it goes sometimes.
|The outboard housing was showing some slack - top right. Stipping it all could have been a nightmare! - Biting the bullet I took an angle grinder to the heavily corroded split coupling ( below ). Even the stainless grub screw needed drilling out - not a promising start.
One and a half hours saw the coupling slide off the shaft. Shaft out - the packing gland sailed off the stern tube - which would not budge off the outer housing - but the fixing bolts prooved worryingly loose, the top one having no backing nut at all. The lower had had the nut conveniently glassed in captive.It then unsrewed from the tube - which sticks through the hull.
The set up is of a solid bronze outer bearing, bronze stern tube,( 3mm thick ), male threaded each end to fit both housings - and the packing gland, again a solid bronze bearing.
Prop shaft, three quarter stainless, seems pretty good at the outer bearing, slight wear through the stuffing box.
T.Norris at Isleworth identified the outer bearing as a standard part they could supply. This would go straight back on my existing fitting holes and all important captive nut for the lower bolt. I can only reach the inside of this with a one foot extension and at arms length through the small cockpit access hatch. They also felt that the wear on the inboard housing wasn't too much of a worry, as the packing gland tends to make up for this - and as such no bearing is essentially needed.
To convert to a water lubricated outer housing would involve altering the fixing arrangements at the transom exit, as they are wider on the bolt holes - also the stern tube would have to be shortened to accomodate the extra width, also probably a step down ring to inch and a quarter.
Basically - it is either, new outer housing, new split coupling ( the one left could be salvaged, but I'm a little worried about upsetting the balance - a new one from R&D couplings is only 40 ukp plus vat ) or - change the whole system, maybe thinking about a pss seal - which I think would need a water lubricated outer bearing.
I'm going with the former for now.
I'm happy with a three quarter shaft, so the split coupling can be re-used at any future change. Also - the shaft is ample length and the prop was very close to the rear housing - so I can drop it back about 40mm - which gives me virgin shaft in the new bearing and allows for space for a prop cutter and maybe a shaft anode. Now is prob the time to decide on that one I suppose.
Jan 04 - still a lot to do by spring!