[Jimbuna]

In RL (on mamy occassions) a destroyer would ram a U-boat (if in close proximity and in a favourable position) in an attempt to breach its pressure hull.

A bonus could result in disabling the U-boat enough to prevent it from submerging rather than destroying it.

Either way, the result was usually the incapacitating the U-boat.

Many escort Captains considered the risk of damaging their own vessels as a result well worth taking.