This game has just horrendously programmed Hedgehog mortars. Ingame theyre programmed at best as a sort of mini-depth charges with more range. Here are some facts
The Hedgehog had four key advantages over the depth charge:
1 An unsuccessful attack does not hide the submarine from sonar. Hedgehogs only explode when they hit something, so missed projectiles fall to the ocean floor.
2 The depth of the target does not need to be known. Hedgehogs are NOT depth charges and do not explode after a certain depth or time. They explode when they hit the target or the ocean floor
3 The weapon gives no warning of the attack. As hedgehogs had no timer there was no delay between the set fuse and the actual depth of the target.
4 A direct hit by one or two Hedgehog bombs was usually sufficient to sink a submarine. Depth charges explode with a depth or time fuse. This at best creates a water barrier between the explosion and the submarine. Hedghogs explode directly against the submarine hulls, with no water barrier to diffuse the blast.
Thats not even including that the Hedgehog had up to 24loaded mortars per launcher.