I dislike the seemingly impotent torpedoes myself and have mentioned it in here before.3 torpedoes to bring a medium cargo down is ridiculous,and sometimes (rarely) it would merely stop dead in the water needing a 4th to send to the bottom.
I think a 25-50% increase to torpedo power is needed,in my opinion.Just look at some WWII footage of UBoat attacks,with ships decimated after a single torpedo impact with gaping holes that you could fly a plane through ! Check my sig picture below,that is what should happen to a ship after a torpedo attack
A question here to anyone that knows - does the game (GWX3) model increased torpedo power as the war progresses as happened in real life?,in which case I can accept the poor quality of them in the early months of the war.