One of your primary duties is to attack convoys and should be secondary only to the safety of your crew and boat.
So yes, I would attack...try to target the 'easiest kill' and dive to safety then after evading (hopefully) any reprisals from the escorts plot a course to intercept the convoy further on in it's journey and have another go
If your lucky or skilful enough you can carry on like this until you run out of eels
Ever the optimist! lol