I have been to the coast and seen the "curve" on the sea but this proves nothing because if you hold a pencil between your index finger and thumb and wobble the pencil about, you get the appearance of the pen being supple (in motion), when it is rigid and flat. (still).
Remember, flat earth isn't still, its hurtling upwards - and also tilting slightly.
There will be a scientific name for this effect you can demonstrate with a pencil, but I didn't waste my time on so-called "science" thank god. I actually want to know things. So I missed out on the name of the effect of shaking a pencil about to make it look curved, big deal.
Anytime some science geek says some big word I do not understand I only need to go look up the definition of that word anyway, then I am at the level of the scientist. People like to sound clever with things like "yaa its circumnavigation yaa" you mean GOING AROUND, you pretentious bastards!
All science seems to do is look for the most mundane answer and go with that. Why does science always focus on the most boring answers all the time? Seems that science is a religion for the most part. A scientist said it so it must be true.