Visible Horizon

[FireHorse]

Well, here's an interesting fact…

On a nominally flat surface like the ocean, the distance to the visible horizon is a function of one's elevation above the water:

h=√(e/0.5736)

…where e is the elevation (in feet) of one's eyes above the water, and h is the distance (in miles) of the visible horizon.

So for someone standing on the deck of a ship, with their eyes only 9 feet above the water, the visible horizon is ~4 miles. But for someone sitting 52 feet up the mast in the crow's nest, the visible horizon is ~9.5 miles.

Okay, so it's probably not especially useful in any circumstances other than exactly these, but there it is. I'm filing it away in my collection of 'Obscure Mathematical Formulae for Weird (but Potentially Useful) Trivia'.