Quote Originally Posted by caravel
The issue is a crusade launched from Castile going via Constantinople in order to get to Morocco.

This is what happens if you cut the Straits of Gibraltar land bridges.
No argument there, and I have to agree that land bridges are necessary to enhance playability - not to mention giving the dunderheaded AI some useful (and obvious) way to get around. I also appreciate your point that sea routes are an unreliable means to link provinces/landmasses. Odd thing is, though, that while the AI is notoriously incompetent at maintaining it's own trade and communication links at sea, it's devilishly clever at interfering with mine at the most inopportune moments. Too many times I've floundered about chasing a single AI ship from one sea zone to another, trying to kill it, while it keeps running away to another zone, interdicting my sea link but never hanging around to fight it out. Guerilla war at sea . . . .