I have tried both and it behaves the same in both instances, weird thing is that my floating object works fine in your demo level, but in my own level both your example boat and my object behaves the same (flies up in the sky).
EDIT:
I just realized the issue is that my water plane is not at Z:0 in the world, it’s at -6000, when I moved it up to Z:0 it works as intended. Is there any way around this perhaps?