The screenshot from SH4 is with the stock game. No environment mods at all
The warships mod won't be compatible with SH4. However there's a bunch of guys working on a total surface warfare mod with VERY accurate damage models and lots of brand new 3d modeled ships. They have depth charges on playable destroyers working, AI subs, and they're even working on getting playable carriers to launch planes! However don't hold your breath for that mod. It's been taking a VERY long time (no offense to the team).
It's actually a little easier to simulate real compartment flooding in SH4. The compartments don't get destroyed as easily. Plus the visual damage effects put Sh3 to shame. I wish I had a closeup of that screenshot. The entire ship was engulfed in flames.