Does Sinking a Ship need visual comfirmation?

Hi lads,

I just started a new campaign with TMO 2.2 enabled.
And on my first patrol, a little west of Luzon , I spotted a taskforce.
Now I quickly went to intercept and I screamed with joy when I spotted the Kongo Battleship amongst the dozens of destroyers, so naturally that became my first and only target, around 36000 Tons I believe.

I opened my 4 tubes and hit the battleship 4 times.
I instantly went to dive and got the hell out of there.

Now my question is, do you need to stay in visual range for a sinking to count?
I noticed the battleship listing quite badly before I went under but since have not gotten a confirmation on a kill, so does it just take a while?
And if it sinks while I'm hundred of miles away, do I still get the credit for it?

I've been searching for the answer to this but haven't been able to find it anywhere, I'm quite confused as to how the system actually works..

Hope anyone can answer this riddle for me

Thanks in advance

Kind regards,