I had played many times with this mod and I have to say: it is GREAT!!!
But, it has a awfull side, and it is its low power weapons.
Let me demonstrate this with a graphic example:
Mission: Gibraltar
Boat: type VII
Year: 1941
As you can see I torpedoed this destroyer once amidship at 17:20 hours, but without visible results, no fire on board and no list.
The DD followed her path at the same speed and direction, so I decided to surface and to finish my job with artillery.
As you can see, a reinforcement appeared on the horizon at the right.
After more than 15 impacts, and my time on the surface almost exhausted, because a second reinforment appeared on the left.
I ran into the DD, a desperate action for desperate times.
As you can see, I dived because the reinforcement were getting closer.
My prey was still moving, and I never knew if she was sunk or not.
Final thoughts:
I need to find out a way to increase the weapon power by 50%, or may be 100%.
DD are basically "cans", they are not armored at all.
It is the only way to fix this unrealistic behavior.

Realism, YES. A handicapped boat, NO.