interesting topic
to spend torps on a dd is not really what i want to do. and i guess, that it is not the only solution for a successful escape

but thanks a lot for the detailled explaination.
brag, your hinds are not bad. the tactis sound very promising...but i already tried a lot of it.
changing course, speed and depth during a wb-raid is what i already have done instinctively. but in most cases without any lasting success...to deal with one dd is not the problem, even he might be experienced. but if there are two dd´s, the situation becomes critical. as they ping you over cross with active sonar, they always have a quite detailled picture of your position and drop endless and well placed series of bombs. and in most cases the 6th or 7th raid was successful to cause heavy damage with a lot of flooding in my boat. at least: no chance to escape...this cant be the way!!!
in ww2 the uboats also had to deal with 2 or more dd´s under water and escaped very often. and note: the most losses of boats where caused by planes, not by dd´s.