An experiment was done with several lighthouses as well. The earth cannot possibly be curved. Both sides walked away in agreement. The tallest lighthouse in America is seen 27 miles out at sea. My gracious, there are so many false mariners in this website.

The Earth curves approximately 8 inches per mile. At 27 miles, you would have a drop of 18 feet. The tallest lighthouse in the US is 207 feet tall, so yes, you can see it at that distance.

Please be careful with the numbers. It might be true that Earth curves some 8 inches in a mile, but the accumulated effect of several miles is not linear. Anyway, 207 feet is a lot and I see no problem at all in seeing a 207 feet tall light house from a distance of more than 27 miles, if you are looking from the observation room of a large ship. It might start to be difficult to see if you are sitting inside a raft.

I made the same mistake of assuming the curvature of the earth was linear at 8 inches per mile.

But it is not. I proved this to myself on a simple diagram. It is a bit more complicated.

And the distance you can see an object of a certain height also depends on high above the ground you are, too.

This chart assumes you are at ground level.

See the chart for curvature vs. distance.

http://www.davidsenesac.com/Information/line_of_sight.html(That is.:

If you were sitting inside that raft , lying flat at water level, you could see the top of something 1 mile away if it was at least 8 inches in height above the water level . But you could only see the top of something 10 miles away if it was at least 66 feet in height above the water level. You wouldn't be able to see the top of that 207 feet tall light house from 20 miles under those conditions, but you shouldn't have any trouble seeing it at a greater distance even if you just stood up on the raft or certainly from the deck of a ship above the water level.

I think this is right, but correct me if I am wrong. This of course is assuming a perfectly calm "flat" sea.)

You can go to the FES Forum for education after all ! Thanks very much for setting me straight !