[Armistead]

For the most part, long as you're a few 100 yards away, you'll be OK, except for ships loaded with things that go boom, fuel, ammo, etc. or large capital ships such as BB's that carry ammo. Loaded ships have a large blast radius and can damage or sink you up to 700 yards depending on which mod you use regarding the damage zones of the sub.

Many convoys are fully loaded with fuel and ammo. You can often see the load they carry on their decks. If you take the time, you can learn what each load out is by how it explodes. Heck, sometime you can torp one ship and the domino explosions from ship to ship can take out several. I think my record is 7 ships with one torp....only you don't get credit for any ship you didn't directly hit, but can be helpful if you time it to take out escorts.

Also be careful about hiding under damaged enemy ships. I torped one and got it stopped, decided to hide under it because of about 12 dd's trying to get me...but US planes came and started bombing it....they finally blew it up and even 300 ft down under it, the explosion blew me up and the ship landed on me....sinking me for good.