LOTR and the Dwarves in the barrel question

So the question is: can you really put a dwarve in a barrel and float them down the river? 

I see numerous problems with this. First, the seal on the barrel has already been broken, so I'm not sure how watertight they would be without resealing them with some kind of sealant. Sure they can float down the river empty, but putting a person in there would weigh them down much more. 

Second: Why didn't the Dwarves push the lids open? I can't imagine the lid would be that hard to remove by simply kicking out with both feet. 

Thoughts? Any coopers (barrel makers) out there with more knowledge than me?

*update: I found this interesting article .