If you see the ship "go behind the curve" in the ocean and it has totally disappeared it has only gone out of your perspective. You cannot see forever!!!
A photon will continue forever until it is deflected. You will either see the ship, or something in the way. You
can see forever.
When the ship disappears, you understand it's because of the curve of the earth.
There is something called atmosphere. You cannot see forever on earth. Your vision is limited.
I have posted video above debunking your ship disappearing evidence.