It does seem that there is no happy medium between surface ships shooting the big guns at each other (which they still don't do correctly), and not seeing a submarine so easily from 5200 yards. Similarly with a night surface attack. If you set sensors up for that, you lose the distance vision of the AI. What gets me, is that if you make an AI submarine that can sit below the surface of the water, the AI on the surface ship "sees" them, and shoots their guns at them, while starting their depth charge run. I don't mean shots from the fore guns, just to keep the sub honest about its periscope use, I mean it's like the sub is on the surface, and they're giving it broadside after broadside, as they "weave" their way in. From what I can recall from my reading, they would come straight on practically, Ahead Flank, with the occasional slight change in course as an anti-torpedo measure, to get to the submarine's "targeted" location ASAP, and drop the boom-boom on them. Drive them deep, so they're ineffective.
There's just gotta be some way to get a better balance... maybe...
