To clarify once more: If you want to set up a naval blockade with ranged units and you want them to bombard neutral units from a distance, you have to set their fire mode to "aggressive" (High Command only, and only for ranged units). If you want to set up a naval blockade by blocking the naval paths with ships or submarines, to prevent neutral armies from moving through, it is now enough to just place them there with their standard setting "fire at will" (free for everyone, standard setting of all units). 2 Armies with "fire at will" setting will automatically fight eachother when they meet, also on the water (usually the moving army attacks first and is thus the one triggering the war). But ranged weapons with "fire at will" won't bombard neutral units from afar, unless they are set to "aggressive".
close enough to be identified or only close enough to know that someone is out there
this would also appy to arty on land