Really cool game concept!
I too experienced heavy stuttering on the ship, though disabling shadows helped a lot. Also i don't know if i missed something, but i experienced an anoying bug where if i chose to stay awake instead of going to sleep, i couldn't interact with the hammock anymore, softlockig the game.
With some more work put into it I can definitely see this game doing pretty well as a full release, as the foundation is already very good!