As everyone else said, the torpedoes track you as I found out in one painful fight with a D'deridex. It launched three heavy plasmas and I simply jumped my Defiant behind the D'deridex, only ot find the torpedoes turn around make their march right into my face since I was heading straight at them at this point...
Not true. Jump behind the target, facing their rear shield facing? If they were heavily engaged with you and reinforced their front(?) facing shield, you'll face a weaker shield to fire at.
Or, in my case, when your GalX appears with your buff/debuffs running, you hit the target in its rea with a pair of 60K strikes from your spinal lance at a 3km distance.
Not entirely useless.