It's not damaged that we know of,
Now those are words to live by ................ "that we know of". In other words, an armchair guesstimate as the shaft has neither been seen nor photographed. I guess this means the prop will be hammered on and vibration be damned.
the 25mm is tapered and the inch isn't.
An untapered 1" shaft. A 1 in. prop shaft without a taper ? ? ? And you believed him ? ? ? The taper on a 1 inch shaft and taper on a 25 mm shaft will be of slightly different gradient as one is imperial and the other is metric.
Basically they said the inch won't work, not only because it's not exactly an inch, but because there's a taper. Thus is has to be custom built. This is what takes 4 months.
And you took the word of the most ignorant supplier you could find ?
What I'm getting at here, amongst all the sarcasm, is that you have made no preparation for either the removal nor the replacement of the prop shaft
should it be required once you are on the hard.
Do you need to drop the rudder ?
Will the coupling bolts come off ?
Do you have clearance to pull the prop shaft coupling off ?
Do you have room to cut the shaft ?
Looking back through this posting, I see no
proof that this is a 25 mm shaft other than what others say that their particular Bene's have. Original owner didn't swap prop shafts for some reason ? Have you measured the shaft within your boat to
positively identify its diameter ?
I'd like to be able to get off the mooring and to winter storage using the engine and only have 4-6 weeks to get the new prop on.
Surely you're not serious ? What are your winters like and what would a winter on a mooring be like ? Maybe become familiar with tow boats in your area, just in case.