Learn English – “Forecastle/fo’c’s’le/fo’c’sle” – number of apostrophes and do you have to contract with speech

The question is about those two spellings for fo'c's'le / fo'c'sle (that is with two or three apostrophes) to identify missing parts for the word forecastle:

• (M-W. (2 only),
• AmDotEL (3 only),
• Collins (2 and 3),
• Century (2 and fokesel)
• and ODO (…unclear to me, both appear).

The Wikipedia article says

[…] but the position of apostrophes is not universally agreed. The positioning of the apostrophes represents deleted letters, thus fo[re]c[a]s[t]le.

How come the 3 apostrophes version wouldn't reflect the sailors' pronunciation ("Spelling fo'c'sle reflects sailors' pronunciation." – Online Etymology Dictionary) or do they simply mean in relation to the full word?

The "t" in castle is not pronounced but it is still part of the word; is it because of this we have the two apostrophes version (all other missing letters must be pronounced)?

Ngram shows 2 is more frequent, but 3 is there too.

Secondly is it true that no native speaker will ever utter "forecastle"¹, as in never (to describe the part of the spar-deck of the ship forward of the fore rigging)? What is the state of the language on this?

_{1. I saw Mutiny on the Bounty (1962) with M. Brando. At some point he says to the sailors "Keep that for the fo'c's'le" but I heard "fox hole", thought that was the name of a pub, leisure time in any case. Then I watched a "remake", Under Siege (Seagal, 1992) and in a scene they're in the control room and they all say fo'c's'le only but there's a diagram of the ship on a screen, and I could read "forecastle", and only then did I get it; so Seagal helped a learner and I'm thankful.}