I have 3 blade
twin spares that a po changed. And now have 4 blade. Also tail shafts carried as ballast. I go to remote
places so keeping them seems a good idea. All manner of props can be changed in the water
. You need some tools to break the shaft nuts and a specialized puller or C-4. Because of the tapered bore, the fit gets very tight over time. But anyone that can dive can learn. I wouldn't do it underwater now because the props are too big and I'm too old.