Huge explosions!

[JEuler]

Just a little of my observations and a question.

I noticed that some ships sink after a hit with only one torpedo with a huge explosion and goes down literally within a few seconds.
This happens usually with ships in convoys: tankers,large merchants and the empire type freighters, sometimes also with other type of ships.
Sinking these ships when they travel alone is a bit harder and I go with a salvo to be sure.
But when attacking convoys I started to use the one torpedo,one ship method because there's a big chance of success.
These huge explosions happens with impact torps (at 3-4 m) and with magnetic also, no matter where I hit the ship.
It could be possible if you hit the engine room,fuel tanks.

But what if you hit the cargo hold?

For the tankers it's ok to explode because they carrying highly explosive material,for the other ships it would be possible if they carrying ammunition or explosives or ...

Is it actually modeled in the game that sinking also depends on what is their cargo?

P.S. I play GWX Gold with enhanced damage effects enabled,maybe that's why is it happening?