Convoy Help.

I would like to try now and rephrase my question, what then tactics are their to attack convoys besides the lie in wait and slip in right under them, or the slip in from the side, or the lie in wait, fire torps from distance and gtfo??

And usually how far away do you guys 'trail' convoys if you plan on attacking them that night? And any other tactics you all use??

Oh and Id like to know on the contact map what the 'dashed lines' mean, I know that looks like a backwards pacman is their listening range since theyre blind behind them like I am?? then Im guessing the smallest one to the front is their asdic?? Sometimes though I see another circle on top of those ones that covers it? Is that radar?? Or visual range??

And adding another question to that, when your hydrophone man picks up contacts and says long range, or medium range or close range what are the approximate 'range groups' hes covering?? Sorry to ask all questions, it just seems lately Ive been seeing nothing but convoys and getting nothing but sunk