Boat (with Impeller) - spiral vase printable

Primary it was just an excercise for boat designing. Then I thought maybe put an impeller on it, which was created by a friend. He use it for a little truck.
Finally we let it swim in a little bowl :-) http://youtu.be/emC3u8R1e5g

And here you can view Oliver's impeller-truck :-) http://www.youtube.com/watch?v=h_ZOYQsWkps