When detected and being hunted by DD's , I usually try to head towards the closest one at flank speed with a torp ready to fire, I wait till its about 800 yrd's away and fire torp , then crash dive to thermal layer and discharge a decoy, then hard rudder for 45 degree's , trim the boat and reduce speed and creep away. Sometimes I get lucky(about 40% of the time) and the torp hit its target.

When I am trying to conserve torp's, I dont fire, and I follow the rest of the above action's.

Thanks