It's August 1940, I'm in the grid BE33 on a VIIB, following a large convoy for almost two days. After four attacks, the only big ship left is the Amunition ship (in fact I hit her in my first attack, but it was a dud

).
The trouble is that I have only two
aft torpedoes left.
What would you do? Attack and hope that one hit will be enough to sink her or a least cripple her enough to fall behind the convoy? Or would you head for home hoping to find a less dangerous food for your eels?
BTW, what would be the beat way to sink the ammunition ship with one torpedo? Go for a classical bow hit, or...? The ammunition ship sounds highly explosive to me.
The convoy is escorted with four destroyers, Hunt I and V&W class, I think. I was able to escape undamaged each time, getting briefly depth charged only once.
Another question. Approaching the convoy for my next attack, I noticed that one ship is still zigzaging at full speed, while the rest of the convoy traveled in straight course, at 8 kt. Is this a normal behaviour, or a glitch? I'm playing GWX 2.1 and I never saw it before. It looks as though she is unable to find her place in the convoy.