81)” The distance from which various lighthouse lights around the world are visible at sea far exceeds what could be found on a ball-Earth 25,000 miles in circumference. For example, the Dunkerque Light in southern France at an altitude of 194 feet is visible from a boat (10 feet above sea-level) 28 miles away. Spherical trigonometry dictates that if the Earth was a globe with the given curvature of 8 inches per mile squared, this light should be hidden 190 feet below the horizon.”
Phony numbers + refraction
Has that really happened? I don't know; Mr. Dubay only presents claims, but no evidence.
(Sources and details for calculations: See #69&70)
Dunkerque light house is actually 66.35m above sea-level (217.7 feet).
Geometrically it can be seen from at least 29.1km away, a boat 10 feet above water can look at least 6.2km far.
A refraction coefficient of 0.33 at a distance of 45km (28 miles) will give you 6.2+39= 45.2 km of added intersecting sight lines. That means after a sunny day over open water you are able to see the lighthouse from that boat. For more on refraction coefficients and why a value of 0.33 for these conditions over open waters is entirely possible, look here:
Mirages and lighthouses.
You know, we've discussed this in the last few points..
Let's just say that the photographic evidence tells us that these are mirages.
Here are a large set of photographs showing the mirage effect in this location.