I know most people don't accept these experiments, but Tom Bishop almost certainly does. Rowbotham and

this guy seem to base a lot of their flat earth proofs on the idea that the surface of water must be flat, and that plumb cords must always be perpendicular to a flat horizontal. That means that all the experiments in question could possible do is prove that we do not live on a round earth with flat water. Duh. In order for these experiments to disprove a round earth, they would need to first assume the RET and find a contradiction. That means ALL aspects of a round earth, including a center of gravity, non-Euclidean geometry, and geodesics.

Let me make the immediate connection between a flat water surface and a flat horizontal (as found in Euclidean geometry), being that the water surface is always parallel to the horizontal. But in RET, a horizontal in respects to the earth is not flat. Geodesics show that if a line follows a straight path along the surface of a three-dimensional object (the round earth in this case), it will not necessarily be straight in three dimensions:

http://upload.wikimedia.org/wikipedia/commons/thumb/9/97/Triangles_%28spherical_geometry%29.jpg/729px-Triangles_%28spherical_geometry%29.jpgThis is directly related to gravity. The center of gravity is point in the center of a round earth, according to RET; it does not act in some universal 'down' direction as assumed in these experiments. Therefore, anything relying on gravity, such as leveling tools, plumb cords, and the surface of water would follow this curved horizontal plane, which is equal to the line tangent to the center of gravity at all points on the surface of the round earth. Altitude is also relative to this horizontal plane (which on a round earth follows curvature).

This knocks out all of those 'giant protractor' experiments as well as 'plane' arguments, because when a protractor attached to a plumb cord is level (the level being level when it is tangent to the center of gravity, therefore following the curved horizontal), the plumb cord will always be at the 0 minute mark on a flat earth, as long as the plumb cord falls straight (perpendicular to the tangent of the center of gravity), and a straight-flying plane will never change altitude as long as it remains the same distance from this curved horizontal and is affected by gravity (which it must be according to RET).

Now to the water. Water, being affected by gravity, is said to have a surface parallel to the horizontal. In RET, the surface of water is actually parallel to the line tangent to the center of gravity at that point on the round earth. In non-Euclidean geometry, a surface parallel to a horizontal plane (tangent to the center of gravity) that follows a curve would also follow that curve. Unless water could defy gravity, it's surface would be curved on a round earth. The idea that the water surface is always parallel to a flat horizontal came from observations that were not measured, or measurements at distances too small for curvature observable (the round earth would be too large).

I expect no response from Tom Bishop, because of 'tl;dr' (which is how I feel now that I look at it). I will just link to this whenever Tom or someone else refers to any of these experiments.