Here is a side and front of a boat that would never, ever float.
If you’ve ever seen a ship in dry dock, it is a pretty impressive sight. The way that you get 1 zillion tons of steel to float on open water is to balance the amount of top-side ship with a much larger amount of submerged ship. I tried vainly to capture that concept in the bottom portion of the doodle.
Bear in mind that these “facts” are coming from me, which very easily constitutes a non-scientific source.