Locally, August 1st we had a 70 year old woman return from a two year circumnavigation aboard her Najad 38.
She just departed again October 22nd for her next attempt at a single handed non-stop circumnavigation via the great capes!
She is currently the oldest woman to have done a single handed circumnavigation TWICE. She is headed south for the Horn.
I don't think age is an issue here as long as one has health and desire.
Google S/Y Nereida and Jean Socrates for inspiration!!