wulf, I disagree...just about any torpedo hit is going to mangle up the side of a ship, no matter if it hits the torpedo bulge, hits the chain locker, or whatever. Critical hits are talking about mechanical systems that are damaged - rudder, screws, turbines, etc...
In some cases ships can be damaged by torpedoes and greatly slowed by the mangled hull, even if the ship is still relatively intact. In some cases with carriers, they may not be able to make enough speed to perform flight operations.
Chern