Or if you have crush grinding on the c-less you reduce the diameter in increments and let it outfeed. Turning on its own diameter will lessen the chance of leaving the prop end too far out of whack. C-less will leave far fewer surface imperfections due to the actual cutting process and leave fewer areas for stress risers. I would imagine it was turned to reduce diameter, I guess I was looking at the way I would have done it for myself. If you're hanging a $2k prop on the end of a shaft this long do want everything leaning your way of is everything good enough. I'm not trying to stir the pot but most guys on these forums are not dealing with 250 horse 45 mph boats , spend 10k on polishing and powdercoat and have your prop shaft touched up on the neighbors 10" SouthBend lathe. Looking only to maybe spread a little knowledge and get some thinking going.