Chew
Senior Member.
Flat earthers will quote the height and range of a lighthouse and then claim the light should be hundreds of feet below the horizon at that range if the world were spherical. So therefore the world is flat. But they are assuming the listed range of a lighthouse is the maximum range it can be seen from a ship at sea; it is not.
The range listed is the "nominal range" of the light, i.e. the range the light can be seen when the meteorological visibility is 10 nautical miles. It is solely a function of the light's brightness. Why make a light brighter than it could ever possibly be seen at those distances on a spherical Earth? Fog. A very bright light will still be visible from several miles away in light fog. That was very important in the days before electronic navigation methods became available.
Page 7 of the United States Coast Guard Light List Volume I defines the nominal range of a light:

and page 16 states that the ranges listed in the table are the nominal ranges of the lights:

The range listed is the "nominal range" of the light, i.e. the range the light can be seen when the meteorological visibility is 10 nautical miles. It is solely a function of the light's brightness. Why make a light brighter than it could ever possibly be seen at those distances on a spherical Earth? Fog. A very bright light will still be visible from several miles away in light fog. That was very important in the days before electronic navigation methods became available.
Page 7 of the United States Coast Guard Light List Volume I defines the nominal range of a light:
and page 16 states that the ranges listed in the table are the nominal ranges of the lights: