How does armor work in naval?

So as someone just getting into naval, I don’t really get how armor works. So in ground RB, you’d shoot at armor, and you’d non-pen right? But in naval for some reason, I can HE battleship and make it lose crew in my cruiser. I shouldn’t be able to pen it, but it just does damage.
So how does it all WORK?

Ships are not shooting 70mm shells with fart of TNT inside. Also, ships are not armored all the way around like tanks. Check the armor map in hangar.

Ships have crew outside of the armored areas, like AA emplacements and lightly armored areas. Plus the shells have massive amounts of HE filler which allows them to have higher shrapnel penetration too. Also something to keep in mind for naval, some ammunition will overpenetrate things without massive amounts of armor. Like heavy cruiser/battleship guns with APCBC shells can overpen light cruisers and destroyers without detonating the shell.