I may have this completely cockeyed, but I seem to recall that a good formula for working out how far away the horizon is (and I got this from Pprune, I'll have you know) is
d = 1.17 x sqrt(h)
where (d) is the distance in nautical miles and (h) is the height in feet.
Assuming you're at sea level and about 6 feet tall, you'd be able to see the grand distance of 2.6NM. Someone standing on our two ships would be what, 40, 50 feet high? That would give you about 8 and a half nautical miles.
41,000 feet gives you 237NM, give or take.
Someone tell me I've got this right??