He does have a point.
Sorry, but as a Fire Controlman in the real navy, I'm here to tell you that you'd have a hell of a time seeing a type II or VII sub from 6 km away, at night, no moon, with your eyes or normal binoculars.
Yes, you might pick the sub up on sonar, but that will give you a bearing only. You might get a LITTLE bit of phospherous glow from the sea water lapping at the hull of the sub. But you will have darn little information on range, and any destroyer captain would be INSANE to open fire up on something that he's not sure about!
Radar did change a lot of that, but, as he indicated it's 1939.
I've actually had them open up on me from that distance, under the same conditions, with my engines at all stop, and after my many, many years of experience of actually dealing with weapons systems in the US Navy, my first thought was: "No effing way!"
Change it to daytime, with a sea state of 0, and some very alert watch standers on the ship, and I'll give it to you.
But at night, like that with choppy seas? 3 miles away? with a low profile like that?
Not unless one of my watchstanders on the tower lit up a cigarette, and then I'd have him shot on the spot!
Sorry guys, but this is one area that is unrealistic. And you don't have to take my word for it. My father spent 30 years in the navy, and when I showed him, he said "Bull ****! Ain't no way!"
