[CCIP]

There is a difference in effectiveness by depth (which SH3 doesn't model), but it isn't progressive in the way you describe - the differences of damage radius by depth are actually pretty small in the U-boat's operating range, probably not by 4 times as you describe but more like 1/4 at best for the fatal radius.

You have to also keep in mind that a depth charge actually has multiple effects that do damage, not just blast radius, and they're not all equally affected by depth. The higher water pressure actually magnifies some of the concussive effects for example. And you also have to keep in mind that any minor hull deformation or breach is going to be a lot more dangerous and damaging at depth.

So in short, depth charges are not in any major way less effective based on depth. The main limitation on their effectiveness at depth is accuracy (caused by longer sink times).

Anyway, to make the long story short - unless someone finds a workaround (sort of like h.sie with his .exe fixes), the problem is that SH3 doesn't really model anything about the water physics, and depth charges are just a basic area of effect calculation.