[nathanbedford]

I am entirely with you on this one, there is an urgent national need for oil and a reasonable accommodation must be made by those onshore to provide it. Only Ted Kennedy should be accorded a flawless prospect.

Nevertheless, how does the elevation of the Observer affect your formula?

[Halfmanhalfamazing]

Depending on the elevation and again assuming an 11 mile distance with a 100 foot tall oil rig, it would surely make a small portion of the rig visible.

But keep in mind the limitations of human vision vs distance.(perspective)

What you’d see would be merely a black speck on the horizon that at first you wouldn’t know if it was a boat or anything else unless you sat there for hours and just stared at it and realized that it wasn’t moving anywhere.

Also keep in mind how rigs are built. The highest points of these rigs are often times not the bulk of the platform.

[GOYAKLA]

A very simplistic explanation of seeing and object in relation to the horizon can be seen at:
www.boatsafe.com/kids/distance.htm