Stacked Boats Floating

I have a video at http://www.youtube.com/watch?v=KiGxQmCd08E about it. I summoned 3 stacked boats and they were floating. It freaked me out at first, then I got used to it. Use the command /summon Boat ~ ~-5 ~ {Riding:{id:Boat,Riding:

{id:Boat}

}}