NavList:

Funny, I was recently sucked into a lighthearted discussion about a "Flat Earth Society" that was found online. I was expecting it to be a bit of a hoot, and discovered there is actually a very great "scientific" effort placed in presenting this alternate theory, with a great amount of alternate technical theory presented in papers at great depth.

My comment was indeed related to celestial navigation as well.   I simply noted that my ability to find my way accurately and precisely around the earth using spherical trigonometry requires some explanation.

Universal gravitation also needs rebuttal. The earths gravitational effects of density and mass are only as far as I know only really predictable under a spheroid model. The subtle changes of a pendulum on certain places of the earth are replicatable. I guess you could of course discard Newton completely and develop a new theory all your own. 

Ask a good naval gunner if the earth is flat.  Long range gunnery has to take into account the "apparent" spherical nature of the earth in both coriolis affect and range corrections. Their accuracy is uncanny.  A 16" naval gun has a range of 22 miles or so.  Spherical earth corrections  have been known and used since the dreadnought days. 

This so barely scratches the surface of day to day things that work with a spherical model that I guess I'm personally smugly satisified that the spherical model is functional enough to live with for the moment.