...but, unlike Baldrick's, hopefully this one will work!
We've resolved to solve the Duck's propshaft woes by replacing the flexible coupling; and the date set for this momentous task is next weekend.
We're buying an R&D split half coupling, and a flexible coupling from them.
The plan had been to spend Easter week in Upware, soaking the old Centaflex coupling in oil and using hammers, a vice, and other tools to try and separate the two cones that form the coupling.
However, we've decided to solve the problem sooner rather than later, and hopefully once and for all. It might also let us have more access to the propshaft; at the moment, the flexible coupling is only about 10mm from the face of the oil seal that forms part of the stern tube, so you could barely see the shaft.
We may have to angle grind off an inch or so of the old shaft if it is significantly worn; however, it didn't look conical last time I saw it, so this hopefully may be un-necessary.
Realigning the engine is also going to be interesting, however I've had a few lectures on how to do it from people; the trick is to borrow a set of feeler gauges and to turn the coupling around, shifting the engine infinitessimal amounts until there's a uniform amout of clearance all the way around; which means the engine and shaft are both aligned. Then the coupling is bolted onto the gearbox.
This should make cruising a whole lot more enjoyable, once the propshaft is fixed!