Hitboxes.
You just instantly explode, even though it feels like you're miles away from every object in the game. A mechanic for the water (which is nicely done) for example, could be, that you can graze it slightly, but have a damage meter rise up if you stay in there too long, which will eventually destroy the ship. The scrap you're holding at the bottom of the ship would just get washed away.
Bigger hitboxes for the scrap pieces in general (if you don't have MLG aim, picking them up can be iffy) and a way smaller hitbox for the ship would really make a difference.
I didn't notice anything performance wise, went pretty smoothly for me (others before me mentioned issues).
I really liked the multitasking aspect between trying to not crash into anything, but also clicking away at the screen. And destroying a barrier with the total mass just seems logical. Kudos for making this in UE!
It's really just the hitboxes, otherwise great little project.