If a submarine is at a shallow enough depth to fire its torpedoes, its high enough to get hit by shells.

how about shells falling from a 40-45 degrees can do alittle damage, maybe even restrick that to AP since ap it's self is ideal from going through crap. also a minimal of XX" size of shell

I´m going to start with the most common and idiot (IMHO) argument in NF forums: NF is not real life.

Of course that that a submerge WWII sub in attack position (torp depth) will receive damage from a batlleship shell that explode near to it.
 
You will read tons and tons of most unconsistent arguments about Ss are weak, etc, etc, etc, but never will hear that any sub, WWi, WWi pors war or even a nuclear subs will resist a direct hit for a pre Dreadnought battleship.

It´s clear that a SS can have any armor to resist hit from surface ships shells BUT as maybe in game mechanics is not possible to difference between damages (this was program in WIN98 OS age)  you will hear again and again and again the same arguments.

As I tired to hear the same arguments all over again is the reason why I write this.
Tired to hold brainless arguments.

Last advice, don´t waste your time to suggest common sense improvement. the most posting guys in the community will complain and complain and complain and complain and complain and complain only crying to solve their own problems.