I did it in 15w32c, I bobbed for a minute or two, and took 3 hearts of damage. Oh dear.
However, when i did it, the boat broke too.
The first time i did it, the boat broke and i took no damage(with feather falling IV).
the third time, I let it bob, went to eat breakfast, and discovered me hitting the ground too hard.
Floating boat: Note the gap