help with fixing the shokaku sinking charactoristics

im frustrated by the way the game has the damage model set for the ships.

mainly i want to change the shokaku, it must have a rice paper hull because it sinks every time no matter what with just one torpedo. the hiryu and the taiho sometimes sink with one torpedo but mostly take anywhere from 2 to 4 torpedos to sink. the smaller escort carrier akitsu needs 3 to 5 torpedos to sink and the taiyo only 1 to 2 will sink it.

in trying to fix this i changed the stock setting as follows:

armor - stock 35 << i went all the way to 100 and it had no effect
hit points - stock 550 << i went all the way to 3500 and it had no effect

even with armor set at 100 and hit points at 35000 it sank instantly with only 1 mark 14 torpedo. there is something besides hit points and armor that controls ships sinkability and sinking charactoristics but i dont understand what that is.

i need help understanding whats going on here and how i can change the shokaku to react the way the other fleet carriers do.

im playing stock 1.5 with no mods.