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.

What is refraction, and how do we know it is real?
/https://www.metabunk.org/some-questions-about-atmospheric-refraction.t9086/


https://www.metabunk.org/standard-atmospheric-refraction-empirical-evidence-and-derivation.t8703/#post-205947

https://www.metabunk.org/some-questions-about-atmospheric-refraction.t9086/ https://www.metabunk.org/some-questions-about-atmospheric-refraction.t9086/

https://www.metabunk.org/standard-atmospheric-refraction-empirical-evidence-and-derivation.t8703/#post-205947

Checking the numbers

Dunkerque light house is actually 66.35m above sea-level (217.7 feet).

https://fr.wikipedia.org/wiki/Phare_de_Dunkerque

Geometrically it can be seen from at least 29.1km away, a boat 10 feet above water can look at least 6.2km far.

http://www.ringbell.co.uk/info/hdist.htm
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:

http://onlinelibrary.wiley.com/doi/10.1029/2010JD014067/full

http://200proofsearthisnotflat.blogspot.co.uk/2016/02/debunking-dubay-80-99200.html

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.

http://blog.daimonie.com/2015_11_01_archive.html

A more recent debunking of similar claims by Mr Dubay here
https://www.metabunk.org/explained-443-km-distance-mountains-visible.t8980/#post-209201