It would have been nice to see the actual pictures of the lighthouses at that distance. It also depends what vessel you're observing them from - if it's a cargo ship deck you're up 20m above sea level.

But here's my defeater: if the Earth was flat why do ships have crows nests up on the mast? Wouldn't people be able to see at the same distance from the deck? Were all shipbuilders in on the conspiracy for the past thousand plus years?

It would have been nice to see the actual pictures of the lighthouses at that distance. It also depends what vessel you're observing them from - if it's a cargo ship deck you're up 20m above sea level.

But here's my defeater: if the Earth was flat why do ships have crows nests up on the mast? Wouldn't people be able to see at the same distance from the deck?