[Psycluded]

I find that the ladder-fish are perfect for engaging a convoy head-on or from behind, though the homing fish work well for the latter as well.

I dunno, it depends on your tactics. When I run across a convoy, I try and hunt the warships first, then the armed merchants (if I can figure out which ones are which) and then surface and deck-gun them all down. Homing torpedoes or well-placed "javelins" as you put it are perfect for this job. With the homing torpedoes, get in behind the convoy under cover of darkness and throw homing torpedoes at the escorts as they run search patterns away from the rest of the group. Not guaranteed kills, but pretty good chances usually. Warships make a lot of noise.