Thanks so much, Nerd. I've wondered about the missing lines for years.
I owe you.

What a surprise that the previously missing stanza 4 is so innocuous. And that the other deleted lines are so incoherent. By today's standards the bawdy parts pretty mild.

Oxford includes an appropriate 1874 definition of "scuttle":      

"Scuttles..are openings by which to obtain access to certain compartments when necessary."

For "main hatch," see "The Maid of Amsterdam."

I concur that Tayluer was forgetting, reconstructing, adding, and avoiding, but the text(s) he learned may already have been faulty. Otherwise, I doubt he would have sung stanzas 7 - 9 at all.

As for "stinkpots," more to come.