Attacking a convoy

I would start off with a periscope attack, I only reserve surface attacks for poor weather and at night where your superior surface speed can get you in quickly to make the attack and then then same speed will get you out quicker. An attack tactic pioneered by Otto Kretschmer (U-99) who favoured night surface attacks and within the convoy which managed to cause mayhem and confusion.

I would go after the Pyro's with 1 torpedo, mainly they are quite easy to kill especially with GWX. The Large Cargos would need to have 2 fish each to have a chance of sinking them, although on rare occasions I have managed to sink them with one fish.

So, if there are 2 Pyro's then fire 1 fish each and then with the last two fire at a large cargo or merchant, and aim at the smoke stack - the engine room is in that area of the ship.

You might find that if you can get into the convoy you will be able use your rear fish as it will be able to bear on to anything behind you.

I take it you have a Type VII boat? Once you have fired all fish dive deep and quickly you can use the crash dive option with the "C" key, once you are down to about 80 to 100 meters slow down to minimal speed and run in silent mode ("Z" key) - keep diving down to about 160 to 170 meters. Once there you should be safe from any reprisals from the enemy escorts.