The predicted amount hidden of a distant object over water is a common exercise for flat earthers trying to “prove the earth is flat”. They commonly use the formula “8 inches per mile squared” which was introduced into the flat earth mythos in the 1800s by Samuel Robotham. It is a useful formula for approximating the amount drop of a distant object but is not useful for predicting the about hidden.

http://walter.bislins.ch/bloge/index.asp?page=Eight+Inches+per+Miles+squared+Formula+Derivation

https://flatearthbusted.blogspot.com/2016/08/flat-earth-follies-how-to-derive-8-per.html

Eight Inches Per Mile Squared