The Sea and Ships/Boats and Question about Countries and Other Questions

1. After a certain distance, if you stand on land and watch a boat or ship go directly out to sea, it starts to move down, as if there is a curve there. Why is this? It moves downwards until you can't see it at all.

2. If I go to the far West of Northern Ireland in the United Kingdom, why can I not see North America on a perfectly clear day?

3. Why is it possible to sail around the world and end up where you started if the Earth is flat?

4. How does it work with a compass? 

1. There are hundreds of discussions on this topic. Here's one from 2008.

On the sinking ship, Rowbotham describes a mechanism by which the hull is hidden by the angular limits of the human eye - the ship will appear to intersect with the vanishing point and become lost to human perception as the hull's increasingly shallow path creates a tangent beyond the resolution of the human eye. The vanishing point is created when the perspective lines are angled less than one minute of a degree. Hence, this effectively places the vanishing point a finite distance away from the observer.

The hull is simply hidden because it is appearing at an angle too shallow for the human eye to resolve.

Usually it is taught in art schools that the vanishing point is an infinite distance away from the observer, as so:



However, since man cannot perceive infinity due to his human limitations, the perspective lines are modified and placed a finite distance away from the observer as so:



This finite distance to the vanishing point is what allows ships to ascend into horizon and disappear as their hulls intersect with the vanishing point. Every receding star and celestial body in the night sky likewise disappears after intersecting with the vanishing point.

We know that this explanation is true because it's a fact that a half sunken ship can be restored by the aid of a telescope.

As a ship recedes into the ocean's horizon, distant from the observer, it will appear to the naked eye to sink from the bottom up into the sea after it touches the horizon line. It has been found that this effect is purely perceptual, that a good telescope with sufficient zoom will change the observer's perspective and bring the ship's hull back in full view. This is not possible if the ship were really behind a "hill of water." Hence, the effect which is usually thought to prove the earth as a globe really proves it to be a plane.

It's one of the first and primary proofs of a Flat Earth. The fact that a telescope can restore a half-sunken ship demonstrates that the ship is not traveling behind a convex sea.

2. The air is not "perfectly clear" no matter how "perfectly clear" the day is.

3. Circumnavigation is traveling in a circular path with the North Pole as the center of the circle.

4. How does what work with a compass? Circumnavigation? The compass points north.

I'm not that familiar with Rowbotham, but seems to me, that the further something gets, the shallower angle begins to reflect the sky with a mirror line/ layer of mirage.

1. After a certain distance, if you stand on land and watch a boat or ship go directly out to sea, it starts to move down, as if there is a curve there. Why is this? It moves downwards until you can't see it at all.

To add to Space Cowgirl's explanation. A wave blocks visibility on the ocean. When a ship is close there are relatively few waves to block it. As a boat moves farther away, there are more waves. The chances of these waves being big enough to block the entire boat go up and up until they approach 100%. Once a boat gets far enough away, the combination of poor visibility and ~90% wave coverage means that the boat appears to move below the horizon.