Well, I've never had to use a sextant —and now, I know if my life depends on it, I'm doomed!
Nevertheless, for me, it was a really fun thing to mess with—since I didn't know with confidence what I was supposed to do or how, I just went for it and tried my best. Which — no surprise — it failed me.
If you're seeking feedback — I can say that it does become a little frustrating quite fast. If, somehow, you could divide the process into smaller, easier-to-reach steps — I think it could turn out pretty fun, since I would be receiving direct feedback from the game that I'm making the right assumptions about what the game wants me to do
But, to be honest, this is my first time seeing something like this. It is clear that you have a passion for it. And I'm glad you made this game.