Hello Anglo,
I also never found this thread when looking for it.
I wanted to chime in, as I was looking for the same answer, and almost called you.

I learned the song from "A Sailor's Garland" by John Masefield, 1928 (New York ed.) credited to David Garrick. It was "Heart of oak are our ships, Heart of oak are our men" as of that writing.

By the way, do you know when the slow down on "steady, boys, steady" came in?

SW