My problem with Flat Earth Theory is this: If the Earth is flat then that means if you place a telescope on the beach and be able to see every ship on the sea.
You are misunderstanding perspective. You can't see every ship on the sea because:
1) The atmosphere is not transparent - enough atmosphere will prevent you seeing ships beyond a certain point - think the colour of blue mountains in the distance - the mountains are not actually blue, but begin to get the blue hue as they start to be hidden by the atmosphere with enough distance;
2) Perspective - at great distances, the ships at sea will become very small, and relatively small but close waves will be massive in comparison. Hold a small coin to your eye - the coin is only small, but it is able to shield from vision a large object at a distance, such as a mountain or elephant. The same applies to oceans and ships. I mentioned one coin. Now imagine many such coins (the waves of the sea), which would certainly shield the furthest ships from view, if not already obscured by atmosphere.
Because of the curvature of the Earth you can only se 11 miles (going off memory, may be off).
Ironically, it is this method that easily disproves the ball-Earth. We know from the points 1 and 2 above that we cannot see infinite distances. However, on a ball-Earth, we know that for certain distances, we should
never be able to see objects of certain heights, as they would be hidden behind the curvature of the Earth (i.e. were Earth a sphere). However, the fact is, on clear days (refer to point 1 above) we can see such objects at distances beyond which the objects would be entirely hidden by Earth's curvature (given the respective heights of object and observer), were Earth a ball. Ergo, Earth is flat. Note that such measurements must be taken on water, as only water seeks its own level (land may be subject to unevenness and debate about how level it truly is).
You cannot see every boat on the ocean with a telescope so that debunks it for me.
Refer to the points above. Note also that a boat that appears to have disappeared "over the horizon" (i.e. to a Heliocentrist) can indeed be brought back into view by a telescope. Obviously, there is a limit to such a telescope's ability due to the telescope's magnification, and point 1 above.
That and I have been in a plane before and have seen the curvature of the Earth.
Most seasoned Heliocentrists will admit that the curvature of the Earth cannot be seen from a plane. Although not a Heliocentrist, I myself can attest to this fact.
One more gut punch to flat earth: we have satellites(gps and otherwise) that would not operate under the physics of Flat Earth.
Prove it. Are they really satellites, or weather balloons? If satellites, why are there only ever Computer Generated Images (CGIs) and not actually photographs of real satellites orbiting in space or the sky?
I do not need any more proof than that. It is 100% debunked if you consider what I have said.
Your arguments were easily rebutted. I hope you can abandon Heliocentric theory now.