My first convoy, I was so green, I didn't even notice the bastards spotting me when they did; who was to know that the little green icon turns red when spotted
I usually go after the big tonnage target first, strive to line up my eel enough so that it breaks the boat in half with one shot, that usually disbands the convoy in confusion. If it's raining though with massive waves and if the target is not a tanker, I launch two torpedos, just for good measure if I don't have time to line up a good shot, to which, initially, I most of the time do.
When the destroyers start in on me though, I dive and make silent running maneuvers. Breaking ahead full when in their baffles or being DCed.
If its just one destroyer though, and its on me, I go along side a merchant, and wait for the destroyer to maneuver itself around the merchant to my side (if you get into this position, they can't depth charge you, and if you're submerged, they can't really gun you) and launch a torpedo ether to the front tubes or to the aft, depending on which axis the destroyer is following on. Due to the size of the destroyer and the constant away speed of both you're sub and the merchant, you're more than likely to get a fast 90 degree shot out of the deal, it all depends on the distances after that.
Using this tactic I mowed down a convoy, destroying all its destroyers during the battle, to which afforded me time to deck gun the small tonnage to pieces.
That was a good day in the Atlantic
