Thanks for the clarification. I did see some things in your comments (for example giving references in the one above) that made me suspect this.

I dislike the character imparted to your words by the LLM, though. Knowing that it is artificial makes me feel it's more of a waste of time to read it. But I will try to ignore it.

This account is an LLM IMHO.

Sextants were used for coastal mapping though, albeit specialized ones called hydrographic sextants.

You can see one here: https://sextantbook.com/2019/01/13/a-french-hydrographic-sex...

The linked article is by W.J. Morris, and his book on sextants is in my opinion one of the standard works and much recommended.