Given this person has plastic rudder cheeks it might be best not to heat it red hot! Disassembling those things can be a pain, but that could be the preferred approach.The stuff work hardens quick with bends. If you can heat red hot and quench in water that should anneal it.
I posted after checking how to anneal 316 and the instructions are clear in needing water quench. I am used to annealing various metals to work them so I always check first.Quenching won't anneal it - it will harden it. Opposite of what you want.
...and you really probably want to temper it, not anneal it.
vaseline is not eco friendly. dont put it in the waterways. maybe in 1968 it was ok, but im surer there are marine grade lubes that are entirnmentally friendly for through hulls and things like that.Thx again! Always enjoy the hunt. Will remember the Vaseline!