Thank you for the replies about deck awash.
The night convoy attack: I did some tests the closer I got with been detected was 1800 yards. This distance was in my second attack, port side.
My first attack I was starboard of the convoy, shoot the torpedos at 3500/3000 yards +/-. Did a u turn, shoot my aft tubes and escaped southeast.
Circumvent the convoy and decided to shoot my remaining torpedoes. This time I manage to get to 1800 yards above. Then one of the escorts that was returning to front of the ships, began to shoot flares, the ships began to zig zag.
I only hit with my type 14 torpedos, all my electric ones I missed...
Still having a difficulty get the correct speed of the target.
But in the end, I got 4 ships, 2 tankers, so got the Navy Cross when got back to base!
I am also in favour of a night convoy attack mission for testing and do some crazy things to see the behaviour of the game.