@GoldenRivet
Early in the war the escorts weren't very well organized and many convoys only had one to four escorts. In addition not all escorts would attack the uboat, because they'd leave the convoy defenseless. Therefore if a uboat crew suspected which destroyer was attacking them they could at least give themselves an idea of how many of the ashcans would rain down on them. During the attack all the noise and explosions will probably cloud the judgment and you might estimate a completely different number of depth charges, and counting also gave them something to take the mind off the fear, plan an evasion and probably hope the attack would soon stop. I believe the last thing on their minds then was how they could brag about it later. Every DC attack was potentially dangerous and you shouldn't forget that one single hit would mean that you were inside a steel tube that would implode and you had a pretty good chance of dying by the explosion of the DC, by waterpressure, exposure if by chance you made it to the surface or asphyxiation if you got trapped inside an undamaged section. (Although they still might've bragged about it when they got away)
@Contact
Don't waste your eels on escorts that cannot harm you
.