1 tactic, that I'd relied on... for those persistent buggers.
Just as they've passed by & are marking a turn to come back around. pop the torp door open (either an aft or fore tube, depending on your orientation to them.
) pop the cork to do a emergency blow ballast... making sure to set your depth for peri depth. Nno need to worry about their hearing that... as likely you're by that time, in their... baffles & 2ndly... is not like your telling them, your about... they already know that... since they're hounding you... (If it's a solo DD or DE, hounding you at the time... & not getting tagged teamed by 2 or more
think I have had this also work with 2... but, has been some time. I've since learned early on, to avoid DD's/DE's...
)
Anyway, soon as you start nearing periscope depth... go to the scope, raise it & as soon as it clears water... get a bead on where that pesky sucker is. If, they are still aft end facing you, doing a swing about... then chances are good... to give 'em a slap & tickle lullaby of death.
Make sure that when you pop off that 1 torp.. that it, is set it to 3 meters below their keel, for 1... & if possible... set for fast speed (know the T-II, was only a 1 speed torp... but, if that's all you have then, better than nothing...) & mag det. (best time to do that, is just before you pop emergency blow ballast.)
If successful (which by all rights, their being in close... the torp set to fast... they ain't getting away from death. As 1 torp, is enough to sink a DD/DE.) then, right after... get the flock outta Dodge...
Warships, just like their merchie heinz 57 sea going cousins... their belly, aka keel... was their Achillies heel.
This tactic works best in a...
400-750 meter engagement range setting...
If no other DD's or DE's, are about.. & you're not near air coverage or patrol areas... then you should be safe to pop the cork & surface to make your getting outta Dodge, that much faster... just be mindful to keep a sharp look out for air patrols none the less. Not to mention, other warships that just may be out for your head, to mount on to their walls... in revenge for their fallen comrades you just sent to the bottom...
Hope this info helps...
M. M.