Those huge guns on the Nelson ...
 

are completely real!! I slipped into Loch Ewe the other day, and approached that spot were the Nelson is usually located. I'm not sure what happened, but I got to within about 500m of it and noticed that guns of Nelson were rotating ... towards me! Somehow I must have accidentally tapped the 's' key and didn't notice that I had popped up to the surface. I got 9 rounds of 16' right in the face :rotfl:

Whoa! I never thought of that (Thinking how I can get my friend to believe me when I tell him it's ok to surface and take him out with the deck gun....this has potential!....insert evil laugh here!)

I think that's one of the unrealistic points of SHIII. In real life had one Nelson spotted an U-boat surfacing nearby they won't have waited for the 16'' turrets to turn and fire against the threat...

the U-boat would've been subjected to an immediate hailstorm of 6 inch fire from the Battleship secondaries, tho...and a maremagnum of light fire too. But I doubt they'd have even tried to point those massive guns towards a submarine.

I seriously doubt that they could have got the necessary crew to man everything that would have been required in order to shoot so quickly. And I also doubt the guns could be depressed so low at such a small target. Anyway it was pretty funny to watch.

the sub would have been ripped topieces by heavy machine gun and secondary weapon fire long before those guns would have turned around.

Actually, this DOES happen. Battleships will engage you and other ships with everything they've got, including secondaries.

One time I was making a mission with stationary battleships all around my sub to test out torpedo power. Unfortunately, I failed to realize that I hadn't made my sub submerged. The instant the mission begins I get a "we're under attack!" message. I climb up to the bridge to see the searchlights of the King George V, Nelson, and Revenge battleships all trained on me, and a second later they all open up with their secondaries. Soon they've rotated their main batteries into position, and kill me instantly. Ouch.