I am a Captain of ocean going tugs and long before that, a BM aboard CVN-71. When I was aboard the ship and stood lookout, my visibility was approximately 19 miles. When a vessel first appeared to me, I would only see its mast. Then slowly the bridge structure would appear (we called this hull down) and the finally the hull. THERE IS YOUR FUCKING CURVATURE!!!!
We live on a round planet, deal with it.