It’s pretty much round, as much as most folks would care. Any deeper questions I can dismiss as easily?
I think ‘wake’ might be a confusing term. Maybe we should refer to it as the ‘frothing boundary layer’. if you look at the trail of turbulent water a ship leaves behind, its about 3 times the width of the ship and doesn’t seem to diverge very much
Well, how about the well-known (at least in sailing days) fact that ships’ lookouts up on the mast could see other ships (first sails, then hulls as the ships got closer) before they were visible from the deck?
Clearly, the distance is the same from the deck and the crow’s nest, so that can’t explain how a lookout could see something invisible from the deck. But curvature of the earth does explain it.
Though the other response is that with telescopes and the like, an observer can in fact clearly distinguish between an object below the horizon and an object too small to be resolved with the naked eye. With telescopes, ships do not start as invisibly small points that gradually grow larger and more detailed; they appear above the horizon already at a certain size. Though this is less easily introduced as evidence, since few naval people bothered to write about it, wheras there are numerous accounts of a lookout seeing sails which only later came in view of the people on deck.