So if we can detect curvature only a few miles out to sea, then shouldn't we be able to detect curvature accross the sea?
I happen to believe that the earth starts to appear spherical from the sky, because of atmospheric refraction (the bending of images and light, etc)...
Using the method of measuring two or three objects accross a certain distance from another, minimizes the same problems you get with measuring one object at a distance (on sea) - wind, ocean swell, and local refraction phenomena... Because you can get an average of how high each "ship" is relative to one another, how verticle there masts are and the angles they point away from one another... Doing this experiment on land with a few buildings or flag poles may also work.
Why not use the stars? Measure the elevation angle of the North Star (convenient because it doesn’t appear to move, unlike the other stars in the northern hemisphere), and measure the elevation angle above the horizon. Then move some distance north or south and repeat the exercise. Keep doing this and you’ll get a plot of lots of angles and distances. You’ll find that, for every 60 miles you move in a northerly direction, the North Star rises by 1 degree in the sky.
You’ll very quickly see that the only possible solution that works for all the measurements is a spherical earth and a star that is a long, long way away. Try it on a flat earth, and / or with a star that is only a few thousand miles away, and it won’t work.
This is where the absurdity of FET then comes to the fore. Given that the whole theory is allegedly based on simple observations, when confronted with this very simple observation, FET proponents have to invoke ‘bendy light’, aka ‘EA’, for which they have no explanation, nor any model, nor indeed any proof whatsoever.