Roadrunner, thanks for your recommendations on this question...
From your reply I take it that I need all the items labeled "SS SPKT" plus some Sprocket Guards shown in the box on P45? Any idea how many Sprocket Guards I would need ? (Are these really essential?!). I already have a supply of marine grade s/s cotter pins and finmasts in my spare parts inventory.
FWIW the problem I am trying to get around is that my other half has lost confidence in her Hobie Adventure, not because of any issues that she has experienced but because she has witnessed me experiencing a catalogue of mirage drive breakages in my Adventure.
There was a period of a couple of months last year during which I suffered from breakage after breakage (several cables and fin masts breaking on one or other of our two drives and/or masts coming loose on the "set screw" drive we have) to the extent that it seemed like as soon as I got one problem fixed another occurred one weekend after another. It should be said that I was using the drives pretty hard so I would not expect the breakages I suffered to be typical of more normal usage. She witnessed some of these breakages being a real PITA to fix in the garage, not to mention the frustration associated with the long lead time for the supply of parts here in NZ. The upshot was that she now has a fear that one day I/we will suffer another breakage and won't make it back to shore and/or that she will never be capable of fixing a drive breakage if we became separated or if she were ever to go out on her own.
So to reduce the likelihood of a cable breakage I upgraded my drive to the newer cables & routing which, I understand, put less stress on the cable-chain joints and should make a cable failure less likely. These cables are also much easier to change/adjust than the old version.
Personal experience has shown me that repairing a fin-mast breakage on a "set screw" drive is almost impossible in the garage, let alone at sea, unless the whole sprocket assembly is removed/replaced - I understand this is what "screw-in" drive users also suggest if their masts break. This is far too fiddly a task to risk attempting without returning to land IMHO, probably requires a larger toolkit than I would want to carry on board, and is definitely beyond my wife. By comparison, changing out a broken mast on a drive with stainless sprockets (the "cotter-pin" system) even at sea is a doddle.
While I accept that the "screw in" masts may well be very reliable, IMO the simplicity of maintenance of the "cotter pin" system in the event of a mast failure far outweighs any disadvantage associated with a bit of play in the masts (in fact I see a bit of play as a good thing since it allows the stub of a broken mast to be extracted easily - which is the issue with both the "screw-in" and the "set-screw" systems). Hence the reason for wishing to 'downgrade' the sprockets. At best I might be able to train the other half to change a fin mast and insert a new cotter pin
but at least least I hope that fewer cable breakages and easier maintenance will give her a bit more confidence in her boat!
The other practical advantage I am hoping to benefit from is two almost identical drives - same cables, same masts, same mast retaining system, meaning a common set of spares & (minimal) toolkit on board for maintaining both drives.
Thanks again for your help & guidance.