Died from colision?

[Kumando]

Hi Kaleuns, last night on patrol i was after a lone small merchant surfaced and i shot a stern torpedo strait in her screws and she immediately stoped then i started to turn to finish her off with the deck gun when an english speed boat came up (i already knew inbound warships were coming to my position via hidrophones, had sunked another small merchant not far from where i was) i face towards the speed boat and start firing with the deck and the flak but the damn thing is so fast that i was not geting a hit, only a few rounds from the flak that i was controling myself but not making to much damage, still the little bug managed to kill a men and i was geting real mad when a shell landed near my starbord side, i loked trough the binoculars and saw an armed trawler closing fast ( damn whatch officer didint saw that come) ok time to dive i went to about 30 meters and start walking away from the scene ( the merchant was still surfaced and not moving) the strange thing happened passed two minutes after i start geting the message from my CE we are taking damage and the lights start to flicker i consult the damage report and the front of the boat is completly destroyed and everyone in front are dead and im not hearing a sound of colision and there´s still 54 meters under the keel and seconds later im dead with the explanation by colision and i was like WTF????? I dont know what hapened does someone has a clue? It couldnt be the merchant she was not sinking yet. But the real strange was not even a sound only the lights being crushed.