Thanks all for your help.
We got a local man experienced and resourceful, problem was quickly identified at the output shaft, this enabled us to only take off the
gear reduction part.
Inside we found that the coupling nut had come a bit loose, the worst damage was the coupling fixed to the output shaft by a spline and the had been completely worn (chafed) down to nothing.
We were anchored, unwilling to use the
dinghy to push us into the mariner due to minimal
keel clearance. Feeling vulnerable.
We are repaired now and ready for expected 60
Knot winds today on east coat of Tassy.
Local
Fish and chip van as mentioned by Chiefcoxain is indeed a treat and social epicentre.
Attached Image is the offending coupling.