See my other thread with testing. My basic conclusions were:
In perfect conditions with the 16km mod, the player can see well further than the AI.
However in poor conditions with the 16km mod, the AI can see well further than the player.
Additionally, in perfect conditions, the AI exhibits a fairly wide angle field of view. In poor conditions, the AI sees best mainly in the direction of the bow and very poor to the flanks.
http://www.subsim.com/radioroom/showthread.php?t=129249