A picture of a typical maritime flat earth chart appeared on the screen behind me.
"See the Earth is flat to a mariner. Incidentally there are quite a few more easy points I can give you to prove a flat Earth based on ships alone. Not only did ship captains rely on flat Earth maps to navigate by once, but they also depended on the unique properties of light in order to navigate into a harbor after dark. Before the era of GPS ship captains depended on lighthouses to direct them into port at night. This was done by a series of simple math algorithms in regards to the distance that light travels after dark on an unobstructed night. A ship sailing towards a harbor along a seacoast that they cannot even see spots a light in the darkness. Upon seeing the light they reference a handbook to see which potential lighthouses the light could be originating from based on where they think they are along the coastline. These handbooks contained the exact details of when a particular light could be seen based off of the candle power of the light house's unique beacon. So the first lighthouse beacon is seen and the time is noted. The ship keeps sailing. Before long they spot another beacon of a different lighthouse in the darkness of the night. Consulting their handbook again they now know exactly where they are at sea, because the moment they spotted the second beacon they confirm the identity of the first lighthouse and knowing how far the unique light of each lighthouse travels they now have two reference points by which to triangulate their exact position at sea by. All of this is accomplished some 20 miles or more offshore as that is how far the light source from these lighthouses typically carry on an unobstructed night. This tried and true method of ship navigation is impossible to accomplish on a round Earth, because the distance given the dimensions of a curvatured Earth as provided by NASA dictates that visible light can only be seen from 6 miles away at the most before the dipping of the horizon cuts it off from view and yet sailors, since the time of the Great Lighthouse of Alexandria and perhaps even before have utilized the use of beacons at distances of upwards of 20 miles at sea in order to determine their location and where safe harbors lay."
The audience as a whole was silently still as facts are irrefutable, when they truly are a fact.
"Okay another simple example of using a ship on water would be the illusion of a ship falling over the horizon. It's often used as an argument for a round Earth, but in actuality it's the opposite. So you're standing on the beach and you watch a ship go farther and farther out to sea until it appears to fall over the horizon and disappear from view, hence in your mind the Earth is round, because that's what you've been taught from a young age and you see no reason to question it as that is what your eyes are telling you. But if you pick up a pair of binoculars and look through them the ship that just disappeared from view is immediately back into your field of vision. All that has been proven by the illusion of a ship disappearing over the horizon is that the visible distance of detail that your unaided eye can see has been exceeded. Add magnification and the ship is once more back in your field of view. Sea Level is another great way of demonstrating a flat Earth. There have been multiple experiments done, but just to point to one let's take for instance one performed in England. In England they have these water channels which barges were towed down as a means of transporting goods from one place to another in the past centuries before our modern era. These man-made channels are still in existence and are quite straight in some parts. A simple experiment was done where a man with a spyglass stood in the channel about mid chest high in the water. Another man in a row boat proceeded to row down the channel to a distance of 6 miles. At no point did the man in the water lose sight of the rowboat with the aid of his looking glass. Again this is impossible on a round Earth. Given a circumference of 25,000 miles with a diameter of 8000 miles, given to us by the scientific community of adherence to Copernicus's globe view of the Earth, it is possible to calculate what the curvature of the Earth would be over a 6 mile stretch of flat water. The degree of difference is 18 feet. There is no conceivable way the man in the water could still see the rowboat as from his point of focus on a round Earth the man in the rowboat would have already dropped over the horizon and been out of view. Staying with the curvature of the earth formula as provide by NASA and the scientific community it can be calculated that for every 100 miles traveled there is a drop of 66 feet in elevation. These aren't my numbers these are NASA's, based off of the simple derivation of an earth 8,000 miles through the middle and 25,000 miles in circumference. Taking this formula then what is your answer to basic geography when it comes to the Nile River? The Nile River flows northward in pretty much a straight line for a distance of 1,000 miles and yet the elevation change over that 1,000 mile stretch of river is exactly one foot. According to NASA's numbers though it should be dropping by at least 66 feet in elevation every 100 hundred miles traveled and yet it is not. Again I know these are simple examples, but if you have any such examples to prove to me other than taking NASA's word that they went to the moon please speak up."